Many critics only see the obscene abuses humanity heaps upon the prawn. They can only see the aliens as substitute for black townsfolk; they aren't: you can't deal with them as human and expect to keep your limbs.
It wouldn't work without Sharlto Copley (Wickus) and Jason Cope (Christopher). For all the imaginative range of the film, it works because it is the story of one man. Wickus is fighting to restore his humanity against terrible odds. The gritty realism of the film means terrible odds are just that: he fails. I could not have imagined how a man in alien mecha-armour could be as lonely, frail and pathetic as an aged beggar on the streets.
The film has flaws. The plot has holes. For example the "biological weapon", the mutagenic liquid, serves too many roles. It's hard enough swallowing the idea that the mutagen could also serve as fuel.
That said, this is the best kind of science fiction; it's not a slavish political allegory. This is a serious imagining of a situation we've never dealt with. Cheekily, it includes and debunks a certain style of academic interpretation within the movie itself through the talking heads, while the camera tells a different story.
It's difficult to understand Christopher. He's a prawn from a literal master race, but has little relationship with the masses of drones around him. If he had any power he would presumably instruct them that eating the tires of a human vehicle and then tearing the arm off a human trying to stop you is no way to make friends and a great way to ensure you stay in a hellish ghetto. Yet he's so moved by the medical experimentation lab he stops still in the middle of a gunfight.
The film has extraordinary realism. It looks as effortless as directing a mobile phone camera at something happening right in front of you. Alien devices have a compelling sense of being real objects, part of the same world as the dust and the huts.
The climax of the film had clutching my chair. Wikus takes command of a powerful alien mecha, but it's as forlorn and desperate as a liquor-store holdup gone wrong. It's here that Wikus shows us the best side of humanity in sacrificing himself for Christopher and his son, and Christopher finally realises even drones like these dangerous apes have something in them that is human.