This is a raw depiction of an event that actually happened. And after you stopped rolling your eyes (I do that a lot too, when I read that "based on..." thing), let me tell you that this is as down and dirty and especially real as they get. There is nothing glamorized here. Be it the villains, the police or our main character (the latter probably one of the most passive "heroes" you'll ever encounter).
But that's what makes the movie special. It might not be your kind of special, especially if you're expecting this to be an action movie (it's anything but). The loneliness and the way the justice system works is more than irritating. You have to make up your own mind and get out of that anything you want to see. Also there couldn't be any better ending to this movie