I've got Gears of War, and obviously Halo 3, but I haven't got Assassins' Creed (mainly because it doesn't have multiplayer, and therefore I'll just borrow it from a m8 when he's done with it).
The graphics on Gears of War are great, but what I don't like about it is the multiplayer - it's in rounds (like Counterstrike) which I personally don't really like, but there are a hell of a lot of people who do like it, and I'm in a pretty small minority =p. All in all though a good game.
If you want to play then add 'x Numinator x' (that goes for anyone), just make sure to send me a game invite when you see me online, and explain who the hell you are =p.
/Miles