Great mouse, but receiver needed surgery.
592193
Great mouse, but contrary to some reviews I read, you CANNOT get any driver I could find to work on XP.  It still works, just can't program the G buttons..... which arent' needed if you have a G-11 keyboard with 3 sets of 18 macro buttons lol. Haven't bothered trying yet but it would probably fully work on my Win 7 laptop.  Feels perfect in my hand. So glad it's powered by batteries, I have enough things charging 24/7...

Edit April 2018: Taking off a star cause of logitech's inept engineering skills. turned on my desktop today and the mouse wouldn't work, plugged the receiver dongle into many usb ports on two pc's and nothing. I thought it was dead, till I found a youtube video.... Amazon won't allow links, so go to Youtube and look for "How to fix faulty USB Receiver (Logitech Unifying)" by Igor Novak. Basically the little board in the receiver slips and can't make contact and you put a little folded paper under it to push it up. >.<  Works flawless now....
718845
the mouse works perfect except the switch underneath, i had to use some sharp thing like a screwdriver to turn it off or on.
4023340
I really like this mouse and really really wanted it to work for me. The angle of the wrist is perfect. The textured surface is perfect. It is responsive and smooth. I even managed to use X-Mouse Button Control to reprogram the buttons so button 4 became copy and button 5 became paste and the wheel click became double click. This would have been a 5 star mouse...except for one glaring issue. I have bad RSI, and this mouse would have cured it except it caused a new problem because the buttons click so hard. A true ergonomic mouse should also have a soft button click. I thought about trying to take the mouse apart to see if I could modify it somehow, but I have not gotten around to it yet.
I tried to use it and get used to it, but the hard clicking was causing new pains, so now it sits in my desk drawer. Maybe someday when my RSI gets better, I may get it out and use it some.
876169
PREVIOUS REVIEW:  Got sick of my old corded mouse and wanted something more responsive.  The wireless part works great, plugged it into my mac's usb hub, put a battery in, and it started right up.  After a few adjustments for the speed it was perfect... until I kept scratching my hand on something.  What I don't like about this mouse at all is the parts where the seams meet is not aligned very well, and those edges that poke up out of alignment are VERY sharp.  There is one seam that is like a pin pricking the meaty heel of my thumb (seam by the A).  I end up holding it at a strange angle to avoid this annoyance.  The other thing I don't love about it is it seems not to like any of my mouse mats.  I use it directly on the desk so it doesn't feel like it snags or jerks along.  One of the plastic-y slippery areas on the bottom sticker is all crinkly; I've tried smoothing it out and it likes to warp back up again.

For $13 I'll use it until I get really annoyed and then look for something else.

UPDATE:  I did receive a phone call from Anker Direct asking me about my satisfaction with this mouse.  I told them what I put in the review, that I had to sand down the sharp seam and that the slidey sticker was bunchy and not very slidey.  He said that should not be like that, wanted me to be perfectly satisfied, and could he send out a replacement mouse.  I accepted the offer and am now using the new mouse, which has no sharp bits and glides easily.  I must have gotten a bad one previously as this new one is so much more responsive and comfortable to use.

I have modified my rating to 5 stars now as this is what I was expecting in the first place:  a comfortable, low tech, wireless mouse that plugs&plays.  And to boot, Great customer service when I had a problem!  Very pleased.
3393057
I purchased this mouse about a year ago, and had no problems up to about six months after I had it.  Very comfortable in the hand, and the laser works amazing.  My problem lies within the buttons.  After the first six months, the left click was intermittent.  Sometimes it would click, other times, it wouldn't, and even other times it would double click.  I used electronics cleaner and this seemed to clear up the problem.  I seemed to be having these problems again, so I took it out to the garage to spray it out again.  The left click works great again, but to my dismay, the mouse wheel no longer functions.  At the time, I paid $80 for a "precision" mouse.  If this is what Logitech calls "high-quality" I would hate to see something low quality.  I checked the warranty papers, and found that the manufacturer's warranty only covers manufacturing defects.  So if it stops working correctly because of use, they won't fix it for you.  I am very disappointed.  I thought Logitech was better than this.
3224037
I love the feel and performance of this mouse, but my scroll wheel click has gone out twice. The two year warranty has come in handy, and corsair support is very easy to work with. Still, this design flaw has me worried for when my warranty expires in another year or so. I'm on my 2nd replacement in 13 months. Other than that, it's the best mouse I've ever used. Super accurate pointing on a steel series HD mouse pad and a very weighty and smooth feel.
1502611
I love the mouse, but unfortunately the right mouse button broke. It is still under warranty, and razer's support has told me it will be replaced, but after talking to them two times (three if you count the first time I called, waited on hold for an hour to talk to somebody, and then was hung up on) I still have yet to get the promised confirmation email that my replacement is on the way. Each time I talked to them I was told that I would receive an email in the next day or two with instructions on how to proceed with the replacement process. It's now been a week since I last talked to them.
273707
Essentially I like this mouse, however, the right click doesn't work half the time and it rattles like an old milk cart. The battery is a right royal pia to get out. Normally I would return this to the store, but a friend purchased it for me before leaving the U.S. So, for the price, no real point pursuing the matter. Unfortunate really.

Here's a cool thing though. Pictek contacted me an offered a new replacement which I accepted and now all is good in the hood. Thanks Pictek, We love you!
3247277
Great Functions but a little too large for my hand.  I really like this mouse and the vertical and horizontal scroll.  The button on top to zoom is a super nice feature.  I do a lot of web conferences and need to enlarge my screens often.  My only complaint is the pain it causes me.  It wish it came is smaller sizes.  I should probably stop using it since the pain is getting worse but it works so well.
4974902
Logitech is always reliable for me. I have 2 complaints for this mouse:

1. The usb holder on the bottom of the mouse is poorly designed. The receiver is not protected at all and sticks out about 1/2 way.
2. The receiver is too large. Now that the super small receivers are available, I would recommend getting one of those for a netbook/laptop instead of this model.

Haven't used a set of batteries yet, but this auto-installed on XP very easily. Good mouse, price, and overall value.
1100008
This mouse is AWESOME! If you get one that works, as other users have stated at some points this mouse stops tracking and must be unplugged and re-plugged to resume functionality. I'd like to see someone at a CS:GO tourney try that. So I bought one and had this issue then returned it for a replacement and got one that would sporadically jump to the right about half an inch on screen but it never stopped tracking. Sometimes it was repeated and others it would go a few hours before jumping again. I really wanted to like this mouse, its buttery smooth and comfortable but there's only a few things a mouse absolutely needs and that's reliability and accuracy. The mice I received had an issue with both of those things.
4388778
I enjoy the side buttons, but the middle mouse button shorted out and is now unsuable. Luckily the software for the mouse lets me rebind that button.
592047
The mouse is great, but be careful ordering from amazon warehouse deals, mine said there was only damaging to the packaging however the mouse is obviously used, especially the braided cable is worn, cosmetic damage on the buttons, and actual pieces of the braided cable missing.  Everything functions of course, but for the discount it was not worth the damage especially since it was described as only being repackaged.
3224616
I purchased this mouse to replace my older Logitech MX Revolution that was beginning to fail to accept a charge. The customizability of this thing is outrageous, and using the mouse is a real pleasure. Being able to change the DPI on the fly is great and having the tools to change the thumb and palm rest within the mouse itself is convenient.

In games you can tell the difference in accuracy immediately, especially if you're coming from an older, lower DPI unit. The configuration software works well enough but could use some better preset profiles for common usage.

Battery life is much lower than I expected. I get about a weeks worth of charge with moderate to low use. I don't mean gaming though, I mean regular web surfing and such. Based on other reviews stating much longer charges, specifically when gaming a lot, would also produce much longer charges for regular use. In any case, the mouse comes with an extra battery that sits in a charger, so swapping them out is painless and quick.

The left and right mouse button could feel a little more sturdy, but the rest of the buttons are quite sturdy. The palm rest wiggles a tiny bit due to the way in which it's adjusted (it's on a rail with teeth that click into place, kind of like a zip tie.)

Being able to change the weight is a cool feature as well, and if you're not using all of the weights there is a spot to store them in the charging cradle.

My only real gripe about this mouse, and it's kind of major, is that it frequently stops responding after trying to use my computer. I can't see a pattern in the behavior because it seems to happen sometimes if I don't use the computer for 2 days as well as 2 hours. My computer never sleeps, and I just turn the monitor off when not in use, so it's not a computer issue I don't believe. The mouse itself will light up but will not respond. To fix it you have to get down there and unplug the mouse and plug it back in. This is a major pain for a large tower deep under a large desk. No other USB devices connected to my computer do this.

I contacted Mad Catz customer service online and was met with a very difficult to read, broken english response. Their suggestion was to reinstall the drivers, and if that didn't work send it in for warranty. I hate sending things in like this to manufacturers because it often requires me to place a credit hold on my card until they receive the unit and I receive the new one. I've yet to send it in because of this, though to be fair I didn't ask if this is their policy.

I've kept using the mouse and still have no complaints about its operability in every day use, but I might have to just bite the bullet and send it in soon. The Customer service rep told me it has a full 2 year warranty.

I'd recommend this mouse to anyone not bothered by having to unplug it periodically.
1490980
I love this mouse. As an MX 518 user for the last 10 years, I like this mouse even more, but one thing bothers me... the lower side thumb button. This wasn't on the MX518 and my thumb naturally rests halfway on that button. I disable the button, but it still is uncomfortable. This is after 9 months of adapting. Its too bad because the mouse is great otherwise. The new buttons on the side of the LMB are really nice. The free scrolling actually comes in handy quite a lot. Also the Logitech software that automatically switches bindings depending on the active window is AWESOME.
1229237
This mouse felt great in my hand, has an awesome sensor, but I had far too many phantom clicks when I lifted the mouse up and set it back down.  Mouse 2 would be actuated unintentionally which is a big no-no in CS:GO. I had to send it back. I ended up going with a Zowie EC1-A and am extremely happy with it.
1017589
I've had this mouse before, and it was great. But I had to get another one because it got damaged. Unfortunately, when I got this one, the mouse and reciever didn't sync. The USB receiver installed fine, and the mouse turned on fine. But I wasn't getting any movement fromt the mouse. I contacted the seller for a return but didn't receive a response.