Really good but not 96% good. That means critics liked it more than basically every movie except Toy Story 2. As far as summer blockbusters go, I liked Transformers more. But that could’ve also had to do with not being alone in the theater. The thing about Iron Man is that, and this is just a guess, most people really aren’t that familiar with the character and his origins. I definitely knew basically nothing other than that he’s top or 2nd tier in MvC2. This helps because you won’t know that some things are definitely going to happen (i.e. You’re not waiting for a scene where he gets bit by a spider).
As a side note, if you don’t feel somewhat old yet, apparently it’s been 8 years since the first X-Men movie. Also, I stayed after the credits and it was really awkward because it was just 4 of us dorks scattered around that knew to wait, and the cleaning staff was standing in the doorway kind of looking left and right at each other trying to decide whose turn it was to kick us out.
As for the previews I remember, Hulk looks alright, The Spirit looks like Sin City focused on one character (which isn’t a bad thing), Zohan looks like it’s gonna be good for about the first fifteen minutes, The Love Guru looks like it’s gonna be good for nothing, and Indiana Jones looks awesome.