I think a lot of movies suffer from being badly overhyped, so that when you actually get round to watching them - you're sorely disappointed.
American Beauty
Shawshank Redemption
Lord of the Rings
Avatar
With American Beauty, I wanted to see it because it was universally praised, and everyone seemed to agree that it was a pretty good movie. Imagine my disappointment when I finally saw it, and thought it was rubbish. Definitely overrated IMO.
Again, Shawshank seems to be continually at the top of the list of a lot of people's 'best movies ever made' list. Ok it was good, but it was nowhere near as good as people tell you it is.
I saw Lord of the Rings at the cinema, and seriously, I wanted to have a nap. Maybe it would have been different if I'd read the book, but for a complete newcomer to the whole story, I found it overlong and boring. Yet it seems to be praised a lot.
I didn't especially want to see Avatar, but in a pact with my frienRAB (we saw what the others wanted, regardless of own preference) I went to see it. Even I can admit that the effects were amazing, and visually it was incredible, but come on - it has all gone so bonkers! Take away the effects and it's an OK story.