Just glancing through the IMDB Top 250 for some ideas...
Inception - Delicious special effects, but a convoluted, plot hole-ridden storyline that is at once too simple and too complicated to really make much for compelling story, character, or drama
Terminator 2 - The first one is superior in all ways... the kid is annoying, it breaks so many rules of its own universe, and the anti-men themes and dialogue (for some reason completely absent in the first one with the strong, male hero of Kyle Reese to guide things) just kind of ruins it for me
The Dark Knight Rises - None of the interesting character study of the first one, none of the tightly-wound plot or drama of the second one, simply just a mess on all fronts
WALL*E - Pixar has done just so much better, the robots aren't really that compelling, and the brain-dead environmentalist themes and daft science fiction logic just took me out of the moment
The Avengers - Hilariously fun popcorn flick, but, one of the best films ever made? Really? Iron Man is way better as a pure film from the same franchise for innovation, entertainment, and character development
A Beautiful Mind - Not particularly accurate to the life of John Nash, they might as well went with the whole NXNW plot... I probably would have enjoyed that a ton more...
Star Trek Into Darkness - fun, but a mess, and I really don't see the point of "rebooting" the franchise if they're just going to liberally rip story elements from far better originals like The Wrath of Khan
Harry Potter 8 - a franchise that belonged on the page, watching Emma and Daniel and the crowd snore their way through this (they were so bored looking) in their early 20s got old
That would be my obvious list, glancing at it, of overrated Top 250 films.
That is blasphemy! Hands down my favorite Pixar movie.