Short, short review:
It's a good movie. Not as good a Orison Scott Card says it is, but still good.
Why do I say this? Because Whedon's choice of how to heighten the tension in the final act (after they land on the last planet) is a cheap trick. Or an expensive trick, if you want to nitpick. But still, a trick that made me stop living the movie and remember I was watching a man's work.
I'd say more, but it's only been out a week.