Not quite true, it was scripted, however the "majority" of the dialog was improv, just not "all" of it
As an avid moviegoer and sci-fi fan, I thought the movie was great but nothing new and ground breaking like some critics claim. The film's style is nothing new like some people seem to think because there's other movies out there that use it, like the Blair Witch Project which might have been the first blockbuster movie to use that filming style and there's numerous television series that use it too like Battlestar Galactica and soon Stargate Universe. So pretty much they were just following an already increasingly popular idea. I'm rather surprised that the movie had been given a PG-13 rating given the content but I suppose it's because the worst gore was very brief or somewhat off-screen. The action in the movie was great with numerous scenes that were memorable and the special effects were really good for being such a low budget movie. The story, dialogue and acting were good. It was easy to follow what was going on with allowing room for questions to come to mind. Nothing stood out to me as being bad which is always a plus and the story loopholes were kept to a minimum by what I saw. The main character came across as being cool but I didn't pick up on any memorable lines to quote like in many movies, not that it's needed. The man who directed, wrote and did some of the animation for the movie is a big Halo fan and he made some of the advertisements for the Halo games. District 9 he admitted is directly inspired by Halo and before working on D9 he was actually working on a Halo movie. He lost the rights though which is why it never became a reality but with the success of D9, he's been renewed the rights to make a Halo movie. Edit: Never mind about the Halo bit. In a recent interview the creator of D9 said he has no interest in a Halo movie anymore but instead a sequel to D9. Overall I think District 9 is one of the best movies to come out this summer and I'd give it a 7 out of 10.