Pros: Lightweight, comfortable, long cord, easy controls, awesome volume, clear sound.
Cons: Shoddy software, awkward "mounting" (see footnotes below), hard headband padding, shallow ear cups.
First off I have to say, I was pleasantly surprised with them right out of the box. The packaging itself sucked, but that's a moot point. At the end of a good, long (3 meter) and very soft braided cable, sits an almost featherweight set of some of the most impressive speakers I've heard in my lifetime. I live in a block of flats, so headphones are about the only way I can enjoy loud music... In that sense, these fit the bill perfectly, for hours on end without any issues.
For those of you who haven't been exposed to the USB headphone idea, it's not quite as simple to use alongside main speakers without some creativity. On that front, you might want to grab this AutoIT3 script while it's still there. I've downloaded the files and cloned the repo, but I'm still wrapping my head around the au3 syntax.
Onto the headphones themselves.. The inline volume control is absolutely brilliant. It's the perfect size and the right length from the head unit; in a nutshell, you won't battle with finding and adjusting it on the fly, without having to look down. After about an hour of gaming, it will already feel natural. That said, the LEDs separating the buttons is insanely bright... Heck, they even glow brightly on the wall 2 meters from my desk when I've got the lights off. O.o Would be nice to turn them down/off.
The ear cups themselves aren't exactly very deep.. I have relatively flat ears, but the tips still touch the felt cover for the speakers. I imagine for anyone with more "wide spread" ears (no offense intended), it may possibly be a bit uncomfortable. There isn't exactly much padding in there..
Fair warning: The Corsair software for these really does suck. I've removed mine from startup, using only the Windows volume control and the AutoIT3 to "manage" the sound. The only benefit I see is an equalizer, but virtually every soundcard these days come with one of those as well, so that's a moot point.
Overall, I'd give these a 8 out of 10. They are amazing quality for their price, comfortable to use for hours on end, and all round a solid investment. While you won't be disappointed, I'm sure you could get better if you spent that little bit extra.
Note: I listed "awkward mounting" in the cons partly for personal reasons.. My left arm is paralyzed from a motorcycle accident, so I only have one hand with which to put them on and take them off. In that sense, the 90 degree free-swinging sides are a bit annoying. I would have much preferred a (at least gentle) spring pulling them straight.