Quite a few controversial games listed in peoples posts, same for me too I suppose
DRAGON AGE II
GTA IV
Batman Arkham Asylum
Destroy all Humans: Path of the furon (old ones were so much better)
Madden 11 (Latest Madden games are good though)
Army of Two
DRAGON AGE II
Vanquish (utterly repetitive, stupid and tiresome)
Rage
Homefront
DRAGON AGE II
And these are just the games I think are terrible, there's dozens more that would still fall under the "not worth playing" list.