Pixar has created some of the best animated films over the years, but some have missed the mark. Some have been disappointing since they've set the bar so high, in terms of quality story.
http://www.ranker.com/list/worst-pixar-feature-film/lanayoshii,
WALL-E
A Bug's Life
Cars
Ratatouille
Toy Story 2
Toy Story 3
Brave
Cars 2
Monsters University
Inside Out