Yeah, Toy Story 2 could well have been much worse (particularly if Disney had made it on their own without Pixar's help). Still, the non-sequel Pixar films have just been one amazing film after the next (even Cars, which I seemed to enjoy far more than the average reviewer). If I was forced to pick a "worst" Pixar film, it would probably be Toy Story 2 (despite it being so much better than anything to ever come from, oh, Dreamworks animation group).

I was about to write a rant about the inspired awfulness of Leonard Part 6 (Bill Cosby, gone horribly, horribly wrong), but that led me to a Wikipedia page on the worst films ever. Wow. Great list.