ScreeningNotes’s review published on Letterboxd:
This movie right here is why I hold superhero movies to such a high standard. The mostly practical action is obviously great for the way it gives the film a rare tactility, but much more important is the way it realizes that the superhero is not the end in himself, he is the means to something greater. And I don't just mean pulling innocent bystanders out of the way as you endanger their lives with your "real" mission. Here, Batman's "real" mission is the innocent bystanders. He consistently subverts his desires to the needs of Gotham.
He's not only fighting against its enemies, he's fighting to make it the best city that it can be. This is why he saves Harvey Dent, but even more than that it's why he rides off into the sunset. The Dark Knight is such a great superhero movie because it realizes that the most heroic think Batman does is not catching the Joker, but leaving Gotham afterward. He recognizes that the power he wields is illegitimate (Dent's "stand against organized crime is the first legitimate ray of light in Gotham"). He recognizes that the state of exception created by superheroes is ethically unsustainable; in order for them to wield their violence, the rule of law must be suspended (supposedly "only for them," but as the copycat Batmans indicate, vigilantism is inherently self-proliferating). Superheroes are a temporary solution, not a permanent one.
This is where we get the famous final lines of the film: "He's the hero Gotham deserves, but not the one it needs right now." Exceptional power can be necessary, and the fact that Batman is willing to wield it makes him the hero Gotham deserves, but with the vast majority of the city's criminals in prison thanks to Harvey Dent, his services are no longer needed. He must leave Gotham and become a symbol of evil in order to return the rule of law to the city. It's not just that "You either die a hero or live long enough to see yourself become the villain"; more specifically, in order to create a stable society, the superhero must become the villain. Heroes are inherently criminal, they're antithetical to the law that holds the world together.
I need to give it four stars instead of the five it deserves because all the courtroom drama and police procedural stuff is so riddled with dull cliches. How "have a nice trip, see you next fall" made it into the final cut I'll never understand.