The set-up is fun but wholly unbelievable. There's no way the ship would just hang there above Johannesburg for 20 years; it would be crawling with international science agencies, taken over by the UN. And the ghettoization of the aliens in a third world slum? No way. The brutal way they are treated, especially by the multinational corporation that oversees their relocation and the mercenaries they employ feels like a ham fisted moral lesson. This extends to Wikus, whose enthusiasm about the popcorn sound alien babies make when they're incinerated is ridiculous. And is he personally going door-to-door to evict almost 2 million aliens in a shantytown? Is that what the director of a program that size would do? He might do one or two as a photo op. And then of course, when he's on the run, he stumbles into the one shack out of a million where the genius alien has his secret laboratory.
But the aliens are fun. I love their anarchic, unpredictable behavior, their obsession with cat food, the way they rifle through heaps of garbage. This is the most enjoyable, organic-looking CGI I have ever seen. Christopher rivals Gollum in my book as the most compelling and believable CGI character yet.
I would say it's similar to Robocop in the broad strokes of its satire, but there are some elements that exceed that film in their veracity. The way Wikus is treated like an object when the corporate big boys realize how much money he's worth is very disturbing. The Nigerian gangsters who exploit the aliens are utterly terrifying. The Blackwater-like corporate mercenaries are horrifying in their murderous efficiency. It's deeply unsettling to think that the most frightening aspects of the film are those based on aspects of real life in Africa. Do we need a science fiction film to get a sense of what's been going on in the Congo all these years?
I have a prediction to make. This baby has "sequel" written all over it: they left the gate wide open for Christopher's return. If it makes a lot of money, the sequel will have a much bigger budget. The graphics will get even better but the story will get stupid on a Terminator scale. As much as I liked certain elements of the film, there's an eagerness to pander lurking in it that will only get worse in the next one.
I recommend it for its visual inventiveness and a less cardboard cast than most big budget SF films, but it's been oversold as a smart story. It's no eXistenZ, Gattaca or Brazil. Those films are much better written.