I thought the movie was incredible, and I intend to see it again with my dad tonight. The political message was powerful but the movie never devolved to 'preachiness' in order to get its point across. I thought the action sequences were thrilling and well executed and I was very shocked when [minor spoiler alert here] people shot with the alien weapons would just explode [end spoiler].
There were some areas which I initially thought were plot holes, but upon analysis of the movie, seemed to me like shining examples of why Neil Blomkamp did such an amazing job:
[spoilers do follow here]
First off, I thought the whole idea of biometric integration between the aliens and their technology was just brilliant! This civilization is obviously quite advanced, but it's a level of advancement that you would expect to see humans obtain in a mere few decades... A century at most. The idea of using their own genetic material as fuel seems somewhat like scientific hocus-pocus to me, but I can suspend my disbelief that far for a movie this good. After all, the internal logic is flawless. These aliens use their genetic material as fuel since it's something they would always have in abundance (no matter where they go in the universe, they've always got their genetics), and it prevents another species (oh, I don't know... Humans maybe?) from running off with their weapons and spaceships.
Also, the idea that exposure of humans to alien DNA triggers some sort of recombination sequence in which the human DNA is gradually transformed into alien DNA reminds me a lot of the video game Dead Space. In that game's storyline, this alien matter (the DNA from District 9) is some sort of a dormant virus, and once it receives a sample of foreign DNA (humans), it rapidly configures itself to be able to attack that strain and transform it into the DNA of an alien species (in Dead Space it was the necromorphs, but in District 9 it was the "prawns"). I thought that feature made it an incredible plot devise, forcing this unsympathetic human to literally walk in the aliens' shoes.
It also made me think about the genetic similarities between the alien "prawns" and the humans. Both are bipedal creatures with a biopic face, mouth region, and two arms (not counting the 'feelers' on the aliens chests). It seems to me like this alien race would have to come from a planet similar to Earth. After all, they stand in our gravity without any issues (in fact, their athleticism suggests to me that the gravity on their home planet is slightly larger), and they breath our oxygen without any obvious side effects. The fact that Wikus would transform into one of these creatures after only a few days suggests to me that their DNA is similar to humans as well. Obviously the outward appearances are different, but the overall body structure is the same, as is the ability for intelligent thought and communication.
Finally, I was taken in by the aliens' behavior. It is obvious that they are technologically superior to humans in almost every way. They are also far more athletic than people. One alien kicked a person in the chest and managed to cause a cloud of blood on impact through body armor. The question of why these aliens never rose against their human oppressors seems to be a matter of motivation. These aliens are clearly as smart as humans, if not more so, but their willingness to lay down before the humans suggests a severe lack of leadership. This is addressed in the beginning when certain people postulate that the leadership caste of this alien race might have died off (the exception being Christopher Johnson and his son who may be the sole survivors left). Regardless of this though, there seems to be an inability to group think between aliens. While they can communicate between one another, there is not much evidence to suggest that they can work together as humans can to accomplish a goal. In short, they are unable to function as a team, and that is why they are easy to oppress.
All in all, I found Blomkamp's depiction of the alien race to be incredibly detailed. It seems to me that if we ever made contact with another race, the comparison might be something like what I've outlined above. We have the advantage of being adaptable, motivated, and the ability to work as a team, while the alien race has superior technology and physical strength. I saw the potential for cooperation between those two races to be quite relevant. Too bad the poor guys landed in South Africa instead of someplace more diverse and open-minded. I'm really looking forward to a sequel in which the alien mothership returns to earth after three years to help Wikus and either seek retribution against the humans who oppressed them, or to help the rest of their species get off this rock we call Earth.
[end spoilers]
Whew... Didn't mean to write an essay. It just sort of turned out that way. Anyway, these are just some thoughts I had about the movie.