Halo 2 was pretty good and that was on the plain XBox. I definitely want to see how the 360 handles the new graphics. Story wise Halo 2 was weaker, since it was not all Master Chief action, but the Arbiter was the final battle. Halo 1 was the reason I got the XBox. The last battle or the escape was the highlight to that game, just learning to drive the Warthog was necessity.
H3 will have 4 player online-coop, the Forge (for multiplayer), Online Multi-player combat. Also on sale will be the Halo 3 Edition 360, controllers, earpiece, and Zune. Damn, I wonder who's getting the Legendary set?