So just saw this last night and I was quite impressed. Robert Downey Jr. does a good Stark, and over all the acting was great. The movie was pretty awesome and really the only gripe I had with it is they spent too long building the suit I think, and not enough time actually showing some action. The fights were awesome but they could have had a little bit more added to them I think.
Though according to wikipedia the whole cast has been signed on for 2 more sequels making an Iron Man trilogy.