Really really great. I might go as far as to say it was the best superhero movie I've seen. And a great film in it's own right. For those who havent seen it, I highly recommend checking out the viral campaigns. I think they really enhanced my enjoyment of the film.
http://www.thebentbullet.com/#!/home
http://www.25moments.com/
http://www.trask-industries.com/#/home