Saw this yesterday. I was underwhelmed frankly. I'm not a huge robot-fight fan, and even in that light, I would have liked to see Iron Man kick more ass. Movie-wise, it was alright. Robert Downey Jr. was great for the role imo. I don't care about whatever the hell his personal life entails.
However, the whole movie was like a prelude. It had some fun action, some technogeek dream house, some oddly placed Jeff Bridges acting, and on the whole I enjoyed watching it. I say "underwhelmed" because the whole movie I was anticipating the kickass Iron Man song to come on, like in the commercial. It was like... this ticking time bomb waiting to go off, and never did. Made me kinda sad.
As far as comic geekery goes, I have no clue who Iron Man is aside minor information here and there. It's still pretty sweet that Downey Jr is going to continue his portrayal of Tony Stark. That'll really start to tie these Marvel flicks together. Too bad most actors have silly things on their minds, like "career" when opting out of a series.

What else? Oh right, I played the Iron Man demo on PS3, and that... really sorta ruined the 'cool factor' of this movie. Which is unfortunate.