As a functional gaming headset, it's been pretty enjoyable to use. In game, it's very easy to pinpoint enemy locations from gunfire and even footsteps, and is highly immersive. The voice chat features really improve communication if you actually play tactically with friends; having the voice chat mixed centrally makes it so much easier to hear people than the single headphone of the standard xbox headset. Also, having your mic mixed back into the headset means I can speak at a normal, even quiet volume, rather than shout to hear myself over the game sound. Overall, these features make the X11 headset very useful for playing online, particularly in FPS games like Battlefield: Bad Company 2. While, as mentioned, the sound quality could be better, as a functional tool for improving your gameplay and communication, they do very well.
There are a couple of problems, including the build quality, that may affect the enjoyment you'll get from them. Firstly, as mentioned in another review, there is a slight white noise 'hissing' that is clearly audible when no game sound is being played through the speakers. According to Turtle Beach this is an inherent flaw with amplified headsets and microphone monitoring. I've found that it can be somewhat reduced by setting the sound level in the game audio menu to maximum, meaning you can have the headset master volume lower. However, you can't completely get rid of the noise. That said, in-game you should never be able to notice it at all over the gunfire, explosions and ambient sounds. Also, the microphone can be overly sensitive to picking up background noise in the room, and from personal experience will produce horrendous feedback for your friends to endure if you accidentally leave your speakers/TV sound on while using the mic!