I'm going to be completely honest - the first movie was absolute crap. I absolutely hated it, and the only reason I went to go see the sequel at midnight release was because I was invited by my friends right after coming home from college, so it was a perfect opportunity to spend quality time with them.
Needless to say, I was blown away by how much better it was than its predecessor. Iron Man 2 is high on my recommendation list for its intense action and much better (and less corny) storyline. Sure it still had the "bad guy invents new robot, Stark destroys robot" stereotype, but it managed to keep you at the edge of your seat unlike the first movie.
I must say "well done" to Jon Favreau. He really pulled out something great with this movie.