To sum it up for those who don't want to wait for my opinion; it was good. Not great but good.

Ultimately, I thought it started well but, by the last big fight scene, it seemed rather like standard comic book fare. Normally I wouldn't have a problem with that at all but Iron Man from the very beginning sets itself up to be something different. And it is, for a while. The dialogue is casual and natural, the characters are all interesting and their relationships seem very real. This is all good but also seems to be its downfall; when you have characters that seem this real and behave so naturally, you'll have to stray further to make these normal people into superheroes and supervillains. And I don't think it was done enough. Tony Stark wasn't set up to be enough of a hero. Tony Stark and Obadiah Stane's hate and dislike for one another wasn't set up enough (and Stane's acts of supervillainy seemed very generic and standard). It seemed like a little too far to stretch my imagination to fit these two very normal, very reasonable characters into the hero and villain roles they had been put into. They were great characters but average heroes and villains.

A few final notes: the scenes in Afghanistan at the beginning of the movie were great and I think Shaun Toub's role as Yinsen might be the greatest underrated performance ever. The introduction of SHIELD is kind of shaky (and God, couldn't they find a better actor for that main agent?) but if the scene after the credits doesn't give you a tingly feeling, you're probably not human.

EDIT: Oh yeah, and I have GTA4. Yay!