Aliens are stranded on Earth, living as … refugees.

Spoiler warning: If you haven't watched District 9, don't read any further. ;)

Before District 9, 90% of alien movies consisted of aliens invading Earth (Transformers, War of the Worlds, Independence Day) or saving humanity (Transformers, Knowing, The Day The Earth Stood Still).
District 9 takes a unique approach towards aliens by depicting them as refugees, racially prejudiced & mistreated by humans. If you're a movie buff, then District 9 is like an oasis in the desert of remakes, sequels, adaptations & all the stereotypical movies.

The Story 

An alien ship runs out of fuel & stations over Johannesburg in 1982. With nowhere to go, the aliens are initially given refugee status, allowing them to live in a secluded slum, District 9. However, with growing public discontent & fear of the aliens, the South African government decides to relocate them. In the process, a human, Wikus van der Merwe, is contaminated with alien DNA which triggers his transformation into an alien…

The Prawns

Prawn is the racist term used for the aliens, which look nothing like your common aliens. The closest creature resembling it is the Cloverfield monster. The aliens were initially welcomed, but once the humans discovered that the alien technologies, especially the advanced weaponry, used a DNA-based identification, they were quickly segregated.
Without their leaders, the alien community falls apart & each is left to fend for itself. The inevitable comparison with the apartheid system is in fact correct - aliens are subdued, rationed & extorted (against cat food).
This depiction of alien xenophobia is what makes District 9 so different from other movies.

Christopher Johnson - that's the actual name of an alien. As the story unravels, your disgust of the aliens gradually gives way to empathy. But ask yourself this - don't we treat other humans likewise?

The main character Wikus van de Merwe is brilliantly portrayed by Sharlto Copley. The only drawback was his heavy South African accent, but I've heard worse than that.
District 9 is an action movie filmed like a documentary. Once Wikus starts his transformation, the action is non-stop. But most amazing are the plot twists - you're lured to think that this is the end of it, but instead you're caught off-guard as another action sequence begins.

In terms of special effects, District 9 excels (not that we would expect less from WETA). The aliens are life-like (some wear shirts!) & there are enough explosions to satisfy even Michael Bay. The details on the alien mothership are staggering. The greatest achievement was of course the mech battlesuit. Who'd think the prawns were that intelligent?
People who don't like gore should stay away from District 9 because it contains footage of exploding body parts (both human & alien).

While & after watching District 9, you're submerged with questions - how? why? That's because so many plot details were never explained.
Why did the aliens run out of fuel? Why are they so submissive? How can a human understand alien-speak (essentially clicks & grunts). Is that where a sequel or prequel will come in? Neill Blomkamp said he would make a sequel only if the movie is successful enough…

Verdict

When I first read that District 9 is being produced by Peter Jackson, I suspected this was going to be a nice film. I was wrong. District 9 is AWESOME!
The documentary-styled narration with action, special effects & a unique scenario makes District 9 not only the best sci-fi movie of 2009 (I have yet to watch Star Trek Yes, D-9 >> Star Trek!!!), but also one of the best movies of the year. :D
Rating - 8/10