Parasite Eve 2. Not exactly a terrible game, but a total dissapointment compared to Parasite Eve 1. Turned an amazingly innovative action RPG (one of the few gun based rpgs that actually worked in gameplay as an rpg) into a half survival horror half action game with very little RPG effects whatsoever, and was just a general letdown compared to the original game. I did play through it(or rather, trudged my way through it) once, mostly paying homage to the original... Only to find that I'd gotten the "mediocre" ending and missed the "good" ending by one tiny little step as failing to backtrack at one very arbitrary point in the game and talk to some douche that I honestly had no way of knowing about without consulting a faq. I'm one of those OCD twits that checks everything, and still missed it. I have played the original through about 5 times, enjoying both the story and the gameplay greatly, and imo that one tiny oversight is about the only thing that gives the second game any replay value whatsoever, which is NOT worth it.
TL;DR : original game was epic, sequel capitalized on an amazing game and ruined the series, as sequels tend to do. (I was naive, *sigh*)
Also battlefield: bad company. Didn't get very far in the campaign, found it rather boring, bought it for the online which was horribly broken and fail. I'll stick with CoD4 tyvm.
Halo 3. I didn't buy it, my brother did, but I feel bad for him. The campaign was rather awesome, though it's the first and only halo i've played, but similar to bad company, the online was terrible and imbalanced. Honestly very fail though how the highest difficulty was in fact a great deal easier than the normal difficulty due to a prevalance of my favorite weapon (the very overpowered pulse rifle) being introduced in the very first level. Die once or twice to unexpected snipers, kill one and pick up his pulse rifle, and proceed to walk through the rest of the game... wait, what?