I started Tomb Raider: Legend on my 360. I'm very impressed by the gameplay and graphics. It also has pretty solid cutscenes and voice acting. I'm only about an hour in, but I hope they focus more on puzzles and less on combat, although the combat is decent. It's a fun play.
I also played the demo of NHL2K6, which plays exactly like it's previous iteration. That isn't necessarily bad. The presentation before the game was pretty awesome (locker room cut scene got me pumped up.)
Still, I also tried the shootout demo for NHL06. While the shootout isn't a very great indication of how the game will turn out, the new stickhandling system is pretty amazing.
I haven't decided which one to buy next week.