Fantastic movie, but unsettling as well. I think a lot of what is truly wrong with human beings was put on display, and none of it was very far fetched, if at all.
There was definitely some fun to be had, but the wrongness of our attitudes towards these...people/beings/aliens was really sad. I don't think any movie I have seen, at least in recent memory, has made me want to cheer when humans get turned into red mist.
This and the new Trek were really the fantastic surprises of the year, and it was nice to see some good quality sci-fi.