I'm a big Iron Man comic book fan and wasn't too sure about Robert Downey Jr. as Tony Stark but it turns out I had nothing to fear. Downey completely nailed Stark and this is one of the best superhero movies I've seen. It has just the right balance of humor, action and origin story stuff - those are what makes a movie based on a comic book good. Make sure you stay to the end though because there is a surprise after the end credits that will get comic book fans like myself completely stoked.