Halo: Combat Evolved- Great game for it's time
Halo 2: It's single player didnt quite pack as much of a punch as Halo CE, but still good. It's multiplayer was amazing for it's time.
Halo 3: Single player was okay at best... multiplayer was just garbage. Getting on everyday just to hear these 12 year old boys screaming into the mic that sound like girls... No thanks. Although it was really fun to go into MLG and purposely lose just to upset them. But I'd take cod4 / mw2 over Halo 3 anyday.
Halo Wars: A Halo styled RTS, knew it was going to fail.
ODST: Fun for like, what, 1 day? After that you've beaten Singleplayer and are bored to death of firefight.
Reach: Looks nice, but Bungie has let me down too many times already to be excited for a new game.