This thread has become what you'd expect it to be: a list of things people don't like.
Most things are going to be overrated because we're exposed to them so much. The initial interest fades away as whatever it is - TV, film, music - is flogged to death. Simpsons, X-Files... 25 series/1 movie and 9 series/2 movies. That isn't overrated, it is just successful. X-Files after Mulder was poor and Simpsons for the last, say, 10 years, has been a shadow of its former self and the movie was rubbish. The whole thing is not overrated though.
My suggestion is going to be controversial. The Shawshank Redemption. Heralded as #1 of all time on IMDB but really there's nothing to it. Think about that for a second. ALL. TIME. A 9.3 rating on IMDB. Over 2 hours of cliched, sentimental manipulation. True it shows the triumph of human spirit, but it offers nothing new, nothing to challenge the audience and it is not presented in an original way - prison is violent and corrupt; life is hard; people are nasty; friendships are formed over time. A to B to C. The ending is even hinted in the title. It's a dramatic version of a Disney film. It is the equivalent of a warm cup of tea on a rainy day. Not hot tea, warm tea. Cosy and comforting.
Still good, several Stephen King adaptations have been good (Stand By Me is also based on a short story and follows a similar formula), but best/favourite movie of all time? come on, people, watch more movies.
I'm not keen on Man of Steel or Dark Knight Rises either