Avengers, The Dark Knight and The Dark Knight Rises are all pretty overrated. This doesn't mean I don't enjoy watching them, but they're definitely overrated.
The second time I saw Avengers I was actually disappointed with it. It just felt kind of off, like something was missing from it. I didn't feel it's as great as most people seem to say it is.
The Dark Knight had Heath Ledger's brilliant portrayal of Joker. But apart from that the film just wasn't really that good.
The Dark Knight Rises is just full of plot holes and is far too depressing. I don't mind the sombre tone to it, but it goes too far with this and takes away some of the enjoyment.
Thinking about it, Les Miserables (the new film) is really overrated. There were parts I enjoyed, but after seeing it on stage multiple times (and being in productions of it) it felt as though some of the magic was missing. Plus there are too many close-up shots of faces.