Just saw this last night, and it absolutely blew me away. I'd read some negative reviews which kinda got me ready for a disappointment, but thankfully it wasn't to be.
I loved how the movie switched from the documentary style to buddy sci fi and then something quite deeper so seamlessly. At first I thought the film was going to be quite heavy handed in the politics with race and separation etc, but it turned out quite differently. In the end, to me it seemed to be more of a comment on the hopeless self destructive nature of the human race, and the dangers of the profit-first world. When someone like Wikus could become quite a different character though, I found that to be rather hopeful.
A tremendous movie. I hope they don't do a sequel, as this one is so good on it's own, but sadly it's inevitable.