Final Fantasy 7: I have stated my case before, so I'm not gonna beat a dead horse (That's SEGA's job)
Halo 3 (and to a lesser extent the series): The games are pretty good, but they had the unfortunate side effect of contaminating video games forever with annoying squeakers and frat boys.
GTA IV: I didn't think that the game was anywhere near the hype/appraise it received. As Mr. Croshaw pointed out this week, any game that has to spend 3 hours training how to play in a sandbox isn't a good game.
Little Big Planet: I just don't see the appeal. I don't get it. It was fun and all, but I don't see why everyone is going stark raving mad over it.
MGS4: If I wanted to buy a movie, I'd have paid $30 less and bought a movie. Kojima-sama needs to trim some of his ideas down.
(PS: Smokey the Bear says "Only you can prevent flame wars...don't be a tard)