I had initially bought the G4ME ZERO hoping they would fit the bill for me. I loved many things about them, but I just couldn't do with them being closed headphones. I found a very good deal on the G4ME ONE, and knew I had to give them a swing.
 
Features: just like the zeros, these have an easy and effective volume dial, lift-to-mute microphone, and braided cable. Unfortunately Sennheiser decided not to use the hinge system they used on the zeros for compact transport, and general adjustability.
 
Microphone: The microphone is by far the best of any gaming headset I have heard. I have had multiple people ask me which usb mic I use when it is simply the headset mic. Once again, the lift to mute feature is great as well. I wish every headset had that feature. The boom also doesn't sit in the line of sight if used correctly. 
 
EDIT: I have found a comparable mic quality (perhaps even a little better) in the V-MODA BoomPro, but it has its own set of limitations and flaws. 
 
Comfort: This is THE most comfortable gaming headset I have ever had. (The zeros were excellent, but the double layer memory foam toward the bottom pushed on my jaw.) The one's pads are a bit fuzzy (could be an itch factor for some), like most velour pads are. The headband is excellent, and the clamping force is lower than most, but they do stay on your head, barring doing jumping jacks. The best part is that they fit around my dumbo ears. VERY few headsets do that.
 
Sound: (Obviously the most important feature) Long story short, they sound half way between a. hd518, and an hd558. If you like Sennheiser, you are in luck. I personally found them to be better than cheapo headphones, and nearly every gaming headset i have tried, but I feel more depth and clarity out of the vast majority of low-end audiophile headphones. For example, the Superlux 668b blow these out of the water with depth and clarity.
 
Conclusion: As far as all-in-one gaming headsets go, these win first for me hands down. The features are exactly what I want. The mic is great, they are very comfortable, open-backed, excellent features...    These would be perfect if they carried the level of sound quality I need. The price is also a huge downside, but I got them for well under $100, so I'm happy.

This has been a very unique audio experience for me. I stumbled across an insane deal on this headset, so I though I would give them a swing.
 
Comfort: As an owner of quite large ears, I can say these are the first to fit entirely around my ears. I wear my headsets hours at a time, so comfort is a must. These are the most comfortable over-ear set I have ever worn. I don't think I get as sweaty using these as other closed headsets I have used.
 
Audio: I had 'closed headphone' expectations going into these, but came out with a cross-breed feel. The sound stage for a closed headphone is very good. I have no problem locating enemies in CS:GO. In fact, they are better than my last open headset. My complaint about these is that they seem a bit flat and lackluster sound wise at times. For example: the boom of an AWP can sound like a couple of tin cans being dropped if it's the right distance away. The sound is clean, and the bass is not as strong as most closed headphones. The bass, however, sounds fantastic. It is clean, not rumbly and muddy. The sound in a nutshell is a closed headset that wants to be open. 
 
Experience: This headset does benefit from an amp. The impedance is simply too high for most on-board audio. The volume dial on the side as well as a mic that blows most other boom style mics out of the water (yet not quite as good as a usb mic) are fantastic features. I did not have a fantastic music listening experience with these. I have no problem with this simply because they are tuned for gaming. It would be nice to get amazing music quality from such a high retail priced item. No grudge held here. They are still good.
 
I think if you can pick these up for a good price then they are worth every cent simply for the comfort factor. Musically, these are not my cup of tea. Gaming wise, they block out distractions, and still give positional feedback. These were designed with gaming in mind, and for that they are the best I have tried so far.