This is a damned near perfect genre movie.
It's momentum flings the narrative along from plot point to plot point, and the movie is filmed in a way that is fast paced and exciting but not confusing.
Director Neill Blomkamp has a virtuoso sense of how to make a movie exciting without making it dizzying. The cuts are fast, but they jump to things that are readily recognizable, so you get a ton of information without getting lost. It was a heart pounding way to see a movie. In terms of action, the movie has a lot of great "DAMN!" action moments, not to be spoiled here, but they are eye-popping and fast.
In other movies of this past summer (cough-cough-Transformers-cough-cough), the senses are pummeled with too much information, and while I'm sure I'm supposed to excited, I'm just numbed. In addition to how the film is presented, what is presented is engaging and thought provoking without being preachy or overwrought.
There's a lot of heart in addition to some jet black humor about bureaucracy, the story focusing mostly on relocation efforts headed by Wikus van der Merwe, played with amazing authenticity by Sharlto Copley as a man in way out of his depth. He finds a bizarre contraption, and then pushes buttons and such until getting sprayed in the face with mist. Suddenly he is ill, and more importantly his DNA has been altered such that he may use alien weapons, a coveted resource that his company, Multi-National United (Doesn't that just sound sinister?) has been trying to utilize since the E.T.s landed a decade ago.
Wikus is a classic everyman. In fact, seeing his transition from self-interested corporate stooge to self-interested freedom fighter is actually quite compelling. What's more, he never really has a revelation along the lines of "what we're doing is wrong," he more or less keeps getting deeper and deeper into the whole mess because of that ever-present self interest. First his career, and then fixing his rapidly changing DNA compel him to do what he does throughout the story, and it's presented in such a way that we the audience can almost pictures ourselves doing the same.
The final frame of the movie is also very compelling, and while it may or may not have set up a sequel, the director would have his work cut out for him if he tried.
The oversimple description to get friends to see this movie? Blood Diamond meets Alien Nation. Even simpler, Blood Diamond with aliens. In fact, you could Cavalcade this movie with Alien Nation, though the cuisine would have to be . . . funky.