I’m always leery when Hollywood makes a sequel to a very good, or high grossing, film. Their track record for getting it right is pretty low. I have been surprised, though, on a few occasions(i.e., Godfather 2, Spider-Man 2, The Empire Strikes Back), just enough to make me ever hopeful.
The trialer for Iron Man 2, due for May release, is out. It looks good, not always an indicator of the movie though.
Check it out: