I thought IM2 was an ass-kicking good time, personally, but then I don't really disect movies, I just go to enjoy them.
The perpetual motion desk doo-dad was one of the best moments, IMO. I could watch Downey play Stark all day.
Also, I have never been to a movie where people applauded in the MIDDLE of the movie (at the end of the Rhody/Stark fight).
And at the end,they applauded, of course. So I think the packed theater I was in thought it was a pretty damn good time.