After seeing District 9, I could tell you about how it parallels the discriminatory politics and economics of apartheid South Africa, or how it tells the story of a man of privilege and his redemption by facing the harsh reality of being scorned and oppressed, or how the CGI and creature effects expose us to the notion that it doesn't matter so much how one looks or even lives as much as it does how one needs and feels.
But I think the best reasoning to see this movie can be expressed through an advertisement:
*New, from Human&OtherCorp! It's the PrawnMech 9000! Utilizing the latest in extraterrestrial technology, this mechanized armored exoskeleton features a direct neural interface allowing you to decimate enemies with a mere thought! No training or understanding of alien language required! Also featured is a direct uplink to your personal mothership, giving you remote control to help allies from afar!
The PrawnMech 9000 is highly resistant to small arms fire of all sorts, allowing one to take thousands of hits and keep on going! It even features a remotely magnetized telekinesis module that enables you to literally take rounds from enemies and fire them right back at them! The suit's reflexively activated movements allow for agile movement in the blink of an eye! You can even catch a launched RPG in midair!
Included in this unit's amazing array of alien armaments is a full set of land-to-land missiles, plasma weapons that liquefy any humanoid creature instantly, highly accurate chain guns, rocket-propelled electric brain-scramblers, and the TK module can even be refitted to lift and fire pigs and other livestock with incredible force!
All of this can be yours for 100 cans of cat food! That's a 10,000 cat food can value, yours for just 100 cans of cat food! Order now!
(Individualresultsmayvary, bodyarmordoesnotguaranteesurvivalundersustainedfire, catchingactiveexplovivesinmidairmaycausebodilydismemberment, largequantitiesofbiofluidmaycauserednessandirritation, consultyourdoctorbeforelinkingupwiththeneuralinterfaceorrectalsteeringcontrol, allHuman&OtherCorpproductsonlyfunctionforthosewithextraterrestrialgenetics, pigssoldseperately.)*
PIG. GUN. Go see it now.