My expecations for this movie going into weren't very high, but it looked interesting so I saw it, and I was very impressed. This is one of those movies that you actually i{can} trust the post-release hype. Most movies these days I can predict what happens within the first 10-15 minutes, but not so much this one.

I saw the movie a week ago so some of the things that stood out to me for critiques were forgotten, but I still have a few: SPOILERS!
Why would a fuel have the ability to transform somebody's DNA? Yes, these are aliens and their technology isn't explained hardly at all, except showing that they are reliant on DNA-sensing, but this fuel that takes twenty years to make completely alters the character exposed. IMHO, only altering parts of him, making a sort of half-breed, would've been more interesting; so he wouldn't really belong to either species until he can be restored.

Near the end, when that little shuttle was taking off, why didn't more "prawns" try to get inside? Don't these things want to go home? Both times, under its own power and with the tractor beam-sorta thing, they didn't react hardly at all. No yelling or running toward the pod, just looking up at it as it left.