Overall Summary: They're wireless via bluetooth, which means the sound gets compressed.  So there goes what little quality they had.  I'd guess the drivers are about 30mm, so nothing near impressive, or even standard.  Back in my peasant days (aka when I played on PS3), they were pretty darn good.  On PC, these are a total joke.  They have a very "V" sounding sound stage, and their sound stage is pretty dang small.  There's also a huge gap in the front of the sound stage, and things coming from 4-5 o'clock, and 7-8 o'clock sound directly behind you.  Same with the front, everything from 11-2 o'clock sounds more right and left. 
 
Pros: Good back in the day, comfort isn't terrible, weight is alright, wireless (sort of a con), works on Linux, wireless range is alright, controls are pretty good and useful
 
Cons: Wireless via bluetooth (sound gets compressed) mic quality sucks, surround sound is horrid on PC, small drivers, horribly distorted sound, ZERO bass,
 
Final Thoughts: Just... no.  These were gifted to me back in my peasant days, but I never would've bought these knowing what I know now.  Then again, this was 5 years ago, so...

Overall Summary: The sound is overall really good.  If you're just looking for gaming surround sound and quality isn't the main concern, these would be pretty good for you.  The price is nice at ~$70, so they shouldn't be out of reach for anyone really.  They feel great, I've worn them for the past 9 months almost for an average of ~9-12 hours each day, sometimes longer, sometimes shorter.  Never really give me any comfort issues.  They're extremely lightweight, and feel really well built.  The sound is pretty good, however I haven't listened to my new headphones yet, so I don't have much to compare them to yet.  The surround sound is great, but I'm sure the quality can be easily beaten by real headphones, not a headset. 
 
The mic has great quality as far as headsets go, and it's pretty flexible.  The ears pivot sideways so they're pretty comfy and portable.  They also have a USB sound card that is completely optional, so if you don't want to use their software, you can remove it and connect via analog 3.5mm jack and either take it on the go, or use your own software for virtual surround sound. 
 
The cable is also 10 feet long, which can get annoying at times.  However, it's a braided cable which is really nice.  It doesn't get tangled at all.  The ear pads and top headrest are also made out of a cloth like material, so they don't make you hot or anything, and they are no problem to wash.  They're very breathable too. 
 
 
 
Pros: Good sound, nice sound stage (with software), firm build quality, washable pads, clear sounding adjustable boom mic, extremely comfortable and lightweight, great for the price
 
 
 
Cons: Software is nice... if it works.  Hit or miss if it'll work with you, but if it works, you're good unless you reinstall your OS.  I tried these on Linux, and oddly enough I only heard sound out of the front two channels.  It's really weird and baffles me to this day. 
 
 
 
Final Thoughts: If you're budget is around the price of these, and you're main focus is gaming surround sound, get these.  If they don't work with your OS, try to battle Logitech's useless support and see what they can offer.  They're most likely not going to do crap, as most of their techs are clueless.  If it doesn't work you can always get it sent back.  However, if they do work (which happens most of the time) then you'll probably be fine, just be careful with updates and stuff, the Logitech Gaming Software is known to have unresolved issues.