I don't really like Return of the Jedi. The detour frustratingly delayed the real story of the movie (rescuing Captain Jack was handled far better), the morality conflict was a little bit too heavy-handed, and the action that offset it was a bunch of ewoks outsmarting stormtroopers in ways that- while I enjoyed- did not really make up for it. That and the love triangle between Leia, Luke, and Han Solo felt just thrown in for the sake of it.
As a movie, I also don't like Revenge of the Sith, often considered the only good prequel. I think the pacing was very poor despite the fact that once he went off the deep end, Anakin went ALL the way. Additionally there's way too much to keep track of. You don't really invest yourself in any of the conflicts because they seem to exist only as an excuse to prove that this is a war. I much preferred the strategy of Empire Strikes Back which managed the same effect by only showing one crucial battle.
I do, however, think that Order 66 was one of the best sequences in the entire saga, and the lightsaber battle at the end was worthy of the last movie. And the lightsaber duels have always been my prime motivation for watching the Star Wars movies anyway.
As an avid Lord of the Rings find, it surprises me to find that The Return of the King was, in retrospect, disappointing compared to the other two. In my opinion, it probably had the weakest pacing, at least for a Peter Jackson movie. The fact that it took like half an hour to end was part of the problem. That said, I can't truly say I didn't like the movie, but that I believe that Two Towers and Fellowship were better movies.
I also feel the same way about At Worlds End despite the fact that I did indeed like the movie, it was just not as good as the two before it because of the pacing.
Do we notice a pattern here? Anyway these are all movies that I still would be willing to watch. For movies I truly hated that everyone liked, I'd have to say anything by Michael Bay or Roland Emmerich (sp?)... along with almost everything with zombies in it.