We saw this movie earlier tonight and I highly recommend it. It was the best movie I've seen in a while. I was going to post a trailer for the film below, but the trailers I saw give away too many plot points, in my opinion (and the one that features interviews with the principals is more tendentious than the movie). I'm glad I didn't see them before I saw the movie, and I'd recommend you don't see them first either.
One nice thing about the movie, incidentally (don't worry, no spoilers follow) is that I didn't recognize any of the actors, who I assume are all South Africans. That enhanced the movie's documentary style. If the Peter Jackson (or whoever produces the inevitable sequel) is smart, he'll resist the temptation to stock the sequel with marquee name actors (I bet Charlize Theron's agent is already making calls). I doubt it though.