Awesome Monitor. I had some issues with the display ...
591154
Awesome Monitor. I had some issues with the display pilot software, but you don't even need it, so maybe just don't bother with it? Up to you I guess. The pre set setting had issues with blacks, just turn the black compensation setting to 0, I think it looks better. Up to you if you max the blue light setting, makes it nicer on your eyes, also don't have max brightness.

I was debating about this and the asus one that my friend has. That one was cheaper, but I am really happy with this.
4666623
So far, I love it. I had to do some color adjustments (to get the display match my other monitor), but after that, the display looks very nice. Also, I have not seen any dead/stuck pixels either! For the price I paid, this looks like a great monitor, and that too, at 2560x1600 resolution!! Quality of the speakers is poor, though. I will update the review if I see any other issues, but so far, I would recommend this monitor...
474379
Got this for my girlfriend. So far, she has loved it (minus one minor quibble).
The colors on it are great for a TN panel (after calibration, it looked better than her previous IPS monitor). The build quality is high and it's quite sturdy. That said, the monitor is quite weighty and she finds it a bit cumbersome to travel with. However, it is manageable.
We had an issue with inverse ghosting on this monitor, but after tweaking a setting related to ultra-fast response time and swapping out the included Display Port cable (I guess we got a bad one), the issue was resolved and everything has been great going forward. She has had a great experience playing Overwatch and other games using this monitor.
4774086
Awesome monitor for the money, super clear picture quality and the refresh rate is awesome.
996212
Resolution is great. Using the 25inch with my macbook pro 15 mid 2015 and the color and contrast is amazing.

One gotcha was the display port connection on the monitor: it doesn't work well.

Using a thunderbolt to DP cable causes the monitor to intermittently get into a state where the display goes black and then not black every 5 seconds or so (the monitor power light is still on so it is not a power issue). This issue does not reproduce when using an HDMI cable.

I think this displayport issue is consistent on the entire line because I have the 24 inch version of the monitor at work and using it with my lenovo t440p (minidp to dp cable) also does the same thing: goes black every few seconds.

Aside from this the monitors resolution is beautiful.
4483925
This monitor was great. 4K looks amazing. I always feel Dell quality control is top notch. There were no dead pixels present, and very minimal IPS glow. Uniformity looked great out of the box, and after playing around a bit with the color settings, it looked perfect (in my eyes). For the price, nothing compares.

I ran it on a single 980 GTX, and gameplay wasn't as bad as people hype it up to be. I know there are those who can't stand any stuttering or whatnot, but if you're mostly playing games that aren't heavily dependent on having perfect response times (i.e. FPS or fighting games, or if you're doing something like heavy competitive GTA V battling or whatever), you probably won't mind. I tested a few games (Arkham Knight, GTA V, Tomb Raider, Bioshock Infinite, Shadows of Mordor, Fallout 4, League of Legends, Heroes of the Storm, Diablo III) on mixed settings between High to Ultra, and they all ran acceptable to me. Especially when you play a game to soak in the beauty of the scene, it's excellent.

There were 2 things I had a grip with. One had nothing to do with the monitor itself, but more to do with the problems remaining with 4K. The scaling isn't perfect, and some games don't scale well. Bioshock, for example, when run in 4K, would not upscale the text, so everything was very tiny. And in League of Legends, the Windows 10 scaling feature would cause all the text in the game to be overly enlarged, to the point that some numbers would overlap each other. The other problem was the DisplayPort issue where, when the monitor went in standby, it would reset the desktop resolution to 640x480, which would screw up my icon placement, window sizing, as well as shift all my programs from my secondary monitor back onto the main monitor. Also, turning it off would result in my secondary monitor becoming primary. I could not figure out how to fix this, as the registry modification tip didn't work on this one (it worked on my LG 34UM95).

With all that said, I decided to return the monitor. I'm sorry I didn't take any photos of the screen in action before I boxed it up. I know i gave it 5 stars, but the decision to return had nothing to do with the monitor itself. I just found myself to be more preferential to a higher clocked monitor (144hz+, gsync) at this point right now, so I decided to go with the XB271HU that was released last month. Though I wouldn't have replaced it for any other monitor if I didn't have the extra $300 the XB271HU cost. 4K was beautiful, and I still prefer its appearance over the XB271HU's 1440p. Maybe I'll go back to 4K once scaling is done right and they start making faster response panels (and after I buy another card or two to run it, haha).

TL;DR
Great monitor, no issues with the panel. Ran acceptable for those who have never used a faster response monitor (TN, 144hz, gsync, etc). Enhanced gameplay experience (beautiful). Had DisplayPort power issues, not a huge gripe. 4K scaling issues still present on some games. Decided to return for the Acer XB271HU, which cost $300 more, because I prefer 144hz (165hz OC) and gsync at this time. If my budget was firm around $500, I would have definitely kept this one.
486855
Great monitor. Only problem is rarely when I turn on my desktop, the screen won't register as being plugged. Not sure if this is a problem with my monitor or the motherboard so I won't impact the rating.
3285717
Great monitor.  I've been using it for about 3 months now.  I Used to have a dual display setup (24" next to a 23").  I prefer using this single display.  No ugly bezels in the middle.  The ultra wide aspect ratio works really well for a desktop environment.  4 full size webpages fit side by side.  Movies fill the screen with no black bars on the top & bottom.  Desk look much more clean and windows are easier to manage.  I use it with a Mac Mini (late 2012).  It took zero configuration to get it to work at the native 3440x1440 resolution with Mavericks.  Yosemite is a different beast.  In order to get it to work properly you need to replace a kext file.  It took some research on apple discussion forums, but it eventually worked and now it has been running perfectly.  Running at full resolution makes webpage fonts a tad to small for my liking, but this is easily fixable with a safari extension.  It's nice being able to fit 35+ apps in the dock that spans the entire length of the screen
There is another version of this monitor that is curved.  At the time it was an extra $500 and it was very difficult to find in the US.  I'm happy I chose this one.
1120555
Best monitor I've ever owned, and I own 3 of them for my setup.

Pros:
IPS with 10 bit color, great for photo editing.
4K, but still large enough to not need text scaling (If you have fairly good vision, I'd say about 30/20 or better). It's like having 4 1080p monitors setup together.
Very attractive stand and back, if you care about that.

Cons:
While the stand looks nice, it's a little wobbly if you're a fast and furious typist like I am. Also no height adjustment.
The inline power brick is a bit annoying. I wish it were inside the monitor itself. Too many monitors today do this.
387844
Excellent monitor. The clarity is amazing. To achieve full 2560 x 1440 resolution, be sure your video card supports this resolution and you use the DVI dual link or DisplayPort cable(s) that come with the monitor. My understanding is HDMI will not support 2560 x 1440. I've had the monitor about 2 weeks and had no high pitched sound issues I've read in other reviews. I would definitely buy this monitor again.
1445530
Like other reviewers, I had problems with washed out color when I first got this monitor.  I played with the adjustments on the monitor itself for hours and was not able to fix the problem, and I thought I was going to have to return it.

It turns out that the problem was with the way the color is processed over HDMI. I changed the digital color output on my video card from RGB to YCbCr444, and the color problem went away: now the display is beautiful. I'm running a GTX560ti, and for me this setting was in the nVidia control panel.

In spite of finally being able to fix the problem, I'm giving the monitor four stars because if it had a DVI input I never would have had this problem in the first place.  Also, the big white lettering on the lower left hand corner of the monitor is really ugly, and the speakers are worthless.

Still, I'm happy overall and I'll be keeping the monitor.
2627856
I've had this monitor for a while now and I've been very happy with it.  I love the size and quality of the display.  I don't mind the "invisible" buttons, I think it makes it look cool and it's not that hard to work around.  The only qualm I've had with it is the internal speakers.  Sometimes they just start humming and I don't have them plugged in to anything and the audio jack isn't touching anything.  When this happens I don't know how to turn off the speakers so I eventually give up and work in a different environment (I use laptops only).  This has only happened a handful of times though.
2286573
Hands down ive never seen more vibrate colors on a monitor.

I played some light titanfall on this and the lag isn't bad I don't notice much delay from it.

The only problem I'm having is the display port. I'm currently using a GTX 970 with the most current drivers. The HDMI works, THE DVI-D works I haven't tried the VGA. When I first plugged it in with the display port it was working great however after I turned off my pc it keeps telling me no signal. I've tried changing from DP 1.2 to 1.1, It doesn't work.
Maybe it's a faulty DP Cable, I don't have a second one, I'll update when I get another DP cable however if you do a google search you'll find out some others also have this problem
NOTE: My monitor came with a Display Port Cable, VGA, HDMI but *NO* DVI-D CABLE regular DVI didn't seem to work with this one so you need a DVI-D
4353199
I've tested this monitor within several games and absolutely love it.  The unit I received has zero imperfections and the panel is absolutely gorgeous.  Moving from 60hz to 144hz with Gsync is absolutely fantastic.  I don't believe it will give you much of an edge in games, but the transition from frame to frame is absolutely apparent over at 60hz display without Gsync.

A word of caution to those using MiniDP:  Make sure you research and buy a VESA DP spec complaint cable.  I originally bought a random DP to MiniDP cable, and was only able to achieve 85hz.  Also I found other glitches when a second monitor was added as the XB270HU would lose signal entirely.  Displayport.org has a database of cables they've tested and verified as complaint.

I can only reasonably say there are two cons with regard to this monitor.  The price is high ($800) for what you're getting.  I'd like to see this unit for $500 and would feel completely comfortable paying that amount.  Also, if you need to turn on Windows scaling for text (as I did on this 1440p screen) note any 1080p monitors attached to your PC will also adopt the scaling.  I really wish there was a way to use scaling only on the 1440p monitor, as my secondary 1080p monitor doesn't look nearly as good with the scaling.
3344791
Great picture and color, a beautiful display with no defects.  The monitor itself is bigger and heavier than many, but I don't mind that as I don't need to move it around.  Two things to note:  If you're planning on using the PIP feature be aware that the sound is only available from the primary source, you will not be able to select the audio for the PIP display.  I found this disappointing.

The only other negative is that the ECO Sensor power saver mode drives me crazy.  BenQ desperately needs to allow the feature to be tweaked by a timer.  If you kick back to watch a video you'll find yourself impatiently waving your hand at the display when it goes black.

Those things aside, I am very happy with my purchase.  Price performance wise, this was a great replacement for my old Apple Thunderbolt display as I migrate to the Windows world.
116675
This is a gorgeous monitor. I was debating between quite a few different 27-inch 1440p monitors but ended up getting this one and I couldn't be happier with my decision. The colors are great although the backlight is set very high out of the box. I don't see any light leakage and have no dead pixels nor any other defects which was one of my biggest fears about purchasing a 1440p monitor. The low blue light feature is great for extended use since it puts less strain on my eyes, especially when browsing the web or working with a word document with a lot of white space on the screen. I have this feature turned on the majority of the time and only turn it off when I play a game or watch a movie. The ports are great and I haven't had any issues with them. The monitor comes with a DP and HDMI cable in the box which is a nice add-on. For those wondering, I mostly use the HDMI port. I have tried the Display Port, but I switched to HDMI to test the built-in speakers and just left the HDMI in. Speaking of which, the speakers are alright and would be convenient if I didn't have other speakers. The monitor height is very easy to raise or lower and it has some sort of a disk on the bottom of the stand which allows me to swivel it..
819051
First off, wonderful monitor and I have little to no complaints. As someone who spent about 3 hours looking at nearly EVERY other possible option there is in this similar price range, let me save you the time I spent:  Get this monitor if you're looking in the sub $200 price range. If you're lucky, you'll catch this on sale for about $180 or so. Let's get some positives and negatives.

Positives:
1. Ridiculous pricing. Definitely worth it for a 144hz monitor. No question. You won't find a better price tag for the size and refresh rate.
2. Stable and well made. No cheap plastic on this guy. Not made of stainless steel and diamonds either though.
3. Great color and brightness. No complaints about quality of display despite my reading some issues other customers had with this factor.
4. Did I mention the price?

Negatives:
1. No adjustable height. Kind of a simple mechanic that they could've added for very little. You can always unmount the monitor and choose not to use the stand, securing it instead to some other fixture... but it would be nice to just have the option.
2. Brightness can be good and bad. And this monitor is VERY bright. There are plenty of options to resolve this though but none built into the monitor.
3. No DisplayPort. This was a pretty big minus for me as the newer graphics cards only output in DisplayPort, HDMI and DVI. While it does support HDMI and DVI, if you want dual 144hz monitors and require a DVI and DisplayPort for output, I don't recommend buying two of these. HDMI nor VGA allows for 144hz refresh rate so having only DVI as the input option is a bit upsetting.

Ultimately one of the best (if not the best) monitor for the price-tag with the refresh rate and response time. No regrets here! Just know what you're getting.