Ok, I didn't think I would like this one, but I loved it!! It's just the right amount of humor and seriousness to make a superhero movie work. I didn't want to see it because of being disappointed with too many superhero movies in recent years ("The Fantastic Four" movies, "Ghost Rider", "Daredevil", "Hulk", etc.)
I wasn't even a big fan of the recent "Batman Begins". I know my opinion is a minority opinion, but I found it boring. In fact, when people ask me my favorite Batman movie, I usually say, "The one with Adam West where he wrestles the rubber shark and can't find a place to dispose of a bomb!" Of the more recent ones, I tend to like the Val Kilmer one.
Anyway, "Iron Man" was a surprise because I'm not a huge fan of Robert Downey, Jr., and thought he was a bad choice. I've changed my mind. Also, the director directed "Elf" before, but he did a great job here, too!
There are a couple of funny cameos and some great lines and apart from suspending your belief on some physics issues, it is a great ride. Must see.