I had to make a separate topic because I cannot say enough good stuff about this movie. It's scary. Parts are under-your-skin disturbing. Parts are hysterically funny.
That being said, I don't want to say anything about this movie. Don't read reviews. Avoid know-it-all spoilers. Just go see it. Try to see it with as little advance knowledge as possible, past the fact that it's a horror movie by Joss Whedon.
You will never, ever forgive yourself if you let some of the story get spoiled for you and experience it out of context.
I cannot wait for this to come out on DVD so I can own it.