Got these to replace some older fans from a coolermaster ...
925075
Got these to replace some older fans from a coolermaster case. These fans are rated for about 5 years until they fail, and that is almost the exact time at which the older ones failed. These are the exact same model as those I just replaced.

These are indeed fairly quiet, though they aren't priced out of the roof
1621645
I got this to replace the fan on my mini-ITX file server where I didn't have much room. This is nice and quiet and has better airflow than the stock case fan, but that was pretty cheap so I didn't need much improvement there.
3082906
Meh. Bought these to replace the AC Infinity fans I bought because those are so LOUD. These are whisper quiet but produce half or less of the airflow of the AC Infinity fans. I guess if you just need very light airflow into or out of your cabinet, these are probably fine. Don't count on major cooling capacity for a larger cabinet with a lot of heat though. They also only run on AC, so if you have any kind of USB temperature control device to turn them on or off, these are not compatible.
2380822
These are really quiet fans for a 140mm fan. Wasn't able to measure the actual cooling impact, but they seem to drop the temperature by a few degrees. I already have 3 other fans, so it is hard to tell. If you want to throw a couple of extra fans, these are great, as they are quite and visually appealing.
3851639
These fans are ok for airflow but don't throw these next to a radiator that's not what these are for.
2923458
Some of the best case fans I've ever had the pleasure of using. They run almost perfectly silent no matter how I use them and still cool very adequately. I prefer them over my Corsair SPs and HFs W/R LEDs, my NZXT rifle-bearings, and some DeepCools I had.
Absolutely great fans with a simple black look that'll work with any build, also includes a molex adapter built into the 3 pin fan headers so if your motherboard doesn't have enough outs it still works off the power supply.
Again, I want to mention how wonderfully silent these fans are, for case intakes, rear outakes, or even as radiator coolers, they've been great. Especially considering the price, four of these for the price of one of the flashier fans. (Such as the Thermaltake Riing series, which I have replaced these with, but still completely recommend the Rosewills)
143529
I bought these to mount to an entertainment center cabinet (closed) that houses a media server. They're fairly quiet (you have to get pretty close to the cabinet to hear them at all), but could push a little more air (this is probably due to them being 80mm fans). They're fairly sturdy, as well.

If I had it to do again I'd go with slightly bigger fans, but for the price these are definitely passable.
3429081
I have a rather large case with a ton of fans, so I was hoping to get these to use in my side door to provide some extra cooling to my 2 video cards (7870s in crossfire mode), but I didn't want to make my case even louder. I had previously hooked up two fans that came with the case to use in the side door vent, and they were extremely loud. When I got and installed these (I actually purchased two), I couldn't tell they were running. Even on the highest setting. I can barely hear them if I put my ear right next to the vent where they're installed.

The only negative is that, as a quiet fan, it doesn't push as much air. It's not a problem for me since I just wanted a little additional airflow for my video cards. But these might not work as well as a single case fan, if your computer tends to run hot. If your computer isn't that warm, though, this would probably be fine.
2169029
Fans work very well for case fans, however the bearings are inadequate, as I have had two fans fail on me. Also, somehow the shielding around the LED's has gone missing around one, also leading to a failure.
2380308
Good fans. I returned them for Fractal fans that went better with my case colorway, but definitely good, quiet, pretty-looking fans
2882677
Purchased two of these for the front of my case (an NZXT h230).

 * Very strong airflow, can even feel air being pushed back out of the front my case through the vent in my slim drive adaptor.
 * Also very quiet when controlled by PWM, while still pushing a good amount of air (my motherboard sets the fans to .75% per degree C on the silent setting, IIRC. Ends up around 1100rpm)
 * LEDs are nice and even, and not too bright. I was afraid to choose blue based on past experience with super-bright blue case LEDs, but pleasently surprised with these.
 * Not a sleeve bearing! D:

 * When controlled via voltage (BitFenix fan controller, in my case), it's a bit louder, and 1200-1400rpm is as low as I can go before it cuts out (without low-speed adaptors). Luckily I have a Noctua PWM splitter that works with these fans.
 * At full-blast, these fans are monsters. They blow a ton of air, but they're really loud doing it.

Overall I'm really pleased with the fan I got, for what I paid for. I could have probably gotten a slightly less noisy fan or slightly better CFM/static-pressure fan for about $5-10 more, but I don't think it'd have been worth it in my case.

Update: one ear fell off when I was moving a fan while holding by the ear. My fault of course (they are pretty hefty fans), but unfortunate nonetheless. Don't hold your jetflo by the ear (or at least grab on both sides) ;)
4150035
Fans received aren't the same as specs in the description (2500 rpm, 29 dba, 35.2 cfm).  Weird, considering a description theoretically describes a particular thing.  Not worth doing anything for the amount, other than noting to self to avoid future annoyances (aren't there enough already?).
3681948
Replaced a few dead fans in my case and they've held up great so far. Not too noisy and decent airflow.
2146017
These fans are dead silent and pulls in cool air . Great case fans, ugly color though.

Better than my loud ass corsair LED fans.
1271665
The two factory fans on my 1060 card were noisy, didn't move much air and had useless LEDs on them. I replaced with two of these DF128015BM fans. I did some custom wiring and had to screw the fans to the factory heat sink after removing the factory shroud. To my surprise these fans draw much less amps than the factory fans. I have no problems running them off the fan header on the graphics card and control the fans speed without issue. I easily dropped 10c on average. Highly recommend!
2142718
Ordered these fans to cool off an amp box and they work great! Great airflow for what i needed. If you need a quieter fan maybe these aren't for you.
18782
I like these fans for Socket 775 motherboards, they keep the CPU nice and cool and it's easy to take off and put on. I hate those twist plastic screws that come with many fans, these have metal screws that that screw into a plate on the backside of the motherboard, nice and firm, the springs keep a constant preassure between the CPU and the heat sink.