Fallout: New Vegas. I really liked Fallout 3, but New Vegas just seemed to linear. Got bored very quickly and never finished the game.

Mass effect is another one I could never really get into, a friend gave me his copies of all the games and couldn't stop raving over them. I got about 2 hours into the first one and realized I didn't care about the characters or the story or what would happen to any of them, so I quit and never went back.