Games you hated but finished anyway
I'm playing Star Wars: the Forced Unleashed now and at first, it seemed pretty fun. However, after a while, the controls started to feel clunky and unresponsive. On top of that, it's painfully repetitive. I see myself finishing it, though, because I've become a Star Wars nut over the summer. It's serving to satiate my Star Wars addiction because my KotOR keeps freezing at this one spot. :(
Another game off the top of my head is Kingdom Hearts 2. After a few worlds, I decided I was extremely bored with it, but trudged on just to see the cut-scenes and to fight Sephiroth.