Most disappointing movie I have ever seen
Star Wars: The Phantom Menace
Indiana Jones and the Crystal Skull
Pirates of the Caribbean Sequels
X-Men: The Last Stand
I have never been disappointed by a movie
Where "disappointment" is the difference between how good you hoped it might be, and how rubbish it was. So you can't have been disappointed by a movie that was clearly going to be terrible in the first place.
Negative points will be awarded to anyone who claims that movies didn't exist. On the grounds that your lack of originality is more depressing than any of these movies. Except possibly Highlander 2.