Let me correct that. Iron Man 2 is one of the rare SUPERHERO movies that is not better than its original. Generally the most sucessful superhero movies in recent years have had sequels that were superior. The Dark Knight, Spider-Man 2, and X-Men 2 were all better than their original films. Iron Man 2 disappointned.
Well, the first Iron Man was a lot more awesome than any of those other franchises' origin films, so I'll accept the slightly less awesome sequel.