I got an Xbox 360 this morning, and have been playing Perfect Dark Zero.
Granted, I'm early in the game, and haven't had a chance to jump into online multiplayer, yet, but I'm thinking there's a reason Microsoft hasn't allowed a review of this game.
It's OK, but so far, feels a bit underpolished. There are some great textures and clever graffiti, but the nightclub scene has got some ass-stupid AI, and it plays for me like a poor man's version of the "NeoTokyo, 2019" level from TimeSplitters 2.
The soundtrack is top-notch, though, the intro is cinematic slick (flipside sexy James Bond-esque), so I may need to give the title more time.
So far, though, not a must-buy-an-Xbox-360-title.