My girlfriend ended up insisting we go see District 9 tonight as it opened. In other words, she's what we call a keeper.
I can tell you, in short: go see it.
It's an honest, intelligent take on an uncommon sci-fi scenario. High tech aliens manage to maroon themselves on earth. I mean, we're talking tech. Humans are more or less modern-day level in here.
Comparatively, the aliens have energy weapons, powered armor, intergalactic travel, and yes, even a gravity gun. One of the sweeter moments in the movie is when someone uses a gravity gun to pick up a slaughtered pig and blow someone away with it.
The movie certainly earns its R rating, though. We see what's basically an anti-personnel bug zapper, and it gets a lot of use. I mean, people literally explode in a shower of gore. But, the violence and well-done CG aliens are not the stars of the movie. It's as it should be; they're window-dressing and a part of the movie. This isn't Transformers where the whole point is "Look at my million-dollar SFX budget." I'm certain that they did spend a heap on special effects, but never to the point that the movie's all about the shiny.
I can't give away much about the plot and scenario without giving it up. I will tell you that it's an original scenario. The plot is not that hard to guess at, but the pacing is well-done. The human lead is a new guy, but he does well in the movie and he is very believable. He is not Billy Badass. He's a paper-pusher, a nice guy thrust into a situation that rapidly deteriorates. Yet, he deals with it well.
The villains...well, I'll just say that you cheer when any of the villain-types get what they deserve. Some of it is very satisfying to watch, if a bit gruesome. (Ok, screw 'a bit.' The aliens are burly enough to rip your arm off, but they'll run off and chew on it rather than beat you down with it. I'm sure they could do the beat-you-down with it, though.)
I will naturally not spoil the ending, but I'll tell you that it's a believable ending. It is not perfectly happy, it is not perfectly tragic, but it is fitting. It keeps the movie from being too black-and-white, and the thing is that the movie does a good job of showing shades of gray and realistic reactions on both sides.
Well, what are you waiting for? Go see it. If all else fails, there's a damned gravity gun and death by flying pig carcass.