Pros: Comfort, isolation, solid musicality, good positioning for a closed can, good mic
Cons: Less competitive in terms of positioning than an open headphone, an amp is needed to make them sound their best
I just grabbed the Sennheiser G4me Zero. It isn't remotely similar to the PC 360 as mentioned elsewhere, apart from the basic shape and approach. The Zero is a closed headphone, while the PC 360 (and G4me One) is open.
If you need headphones that isolate well but still perform well for gaming, the G4me Zero is absolutely excellent. It's comfortable as heck with earpads (interior) measuring ~76mm (3 in) tall, ~45mm wide (1.75 in), and ~25mm (1 in) deep. The earpads are also thicker on the bottom than the top, conforming better to your face than most pads.
I'm listening to some liquid dubstep right now and really enjoying them. Audio quality is up there with Beyerdynamic DT-770 Pros for music, but presenting with Sennheiser's signature sound.
The Sennheiser G4me Zero feels like a closed version of the HD 598 (or a fun version of the 380 Pro), with better bass punch and a little less clarity and soundstage (like you get with any closed vs. open headphone).
If the G4me One is virtually the same but open instead of closed, I suspect it will be the better set of cans for pinpointing people in shooters (open headphones are better for positional audio than closed). That said, The G4me Zero is no slouch, and I am having good success in Battlefield 4 using a Creative X-Fi Titanium HD sound card's RCA outs (in game mode with surround on) into an Objective2 amp.
For super competitive FPS play, I'll pull out the HD 598 with Antlion Modmic instead of the G4me Zero, but I suspect I'll use the Zero for most other gaming.
I'm pleasantly surprised by the G4me Zero with its flashy marketing, stupid name (I can't not say "guh-four-me" when I see the name... yes, I know it's pronounced "game.").
I must admit that I am a bit of a Sennheiser fanboy because of their quality, sound, and--particularly--comfort. I have very tall ears (68mm) that only fit in a few of the circumaural headphones I've tried. I routinely use Sennheiser HD 555, Sennheiser HD 598, Sennheiser HD 650, Sennheiser IE80 headphones, as well as Beyerdynamic DT-880s with Brainwavz HM5 earpads (great pads for large ears--the infamously comfy Beyer pads don't fit me), Narmoo S1, and Logitech Ultimate Ears.
If you pick up the G4me Zero, note that they are 150 Ω and sound better with an amplifier, particularly when listening to music.