I think The Dark Knight is by far the best superhero movie, categorically speaking, I've ever watched on many levels. The story of Batman has always connotatively employed the psychological vagueness of good and evil, especially with the symbiotic relationships between its resident hero and villains, within the dark context of Gotham City which is modelled after Manhattan on a dark, wintry night. There were so many political, social and philosophical issues addressed and yet the plot still remained largely uncompromised (even though liberties were taken with the original comic series, albeit thankfully done in a tasteful manner), making the 2 hours and 40 minutes it ran captivating throughout. Add to that fantastic acting on almost every character's part, especially Heath Ledger, and you get a show as awesome as The Dark Knight.
If anything, the concepts that really hit were dispensed with such delightful twistedness from the Joker. People all too easily succumb to plans, whether they are moral or not, and that is often manipulated by state heads with the ability to exercise lawful coercion. There were so many instances in the movie that highlighted the feebleness and insecurity of human nature once the secure walls of civility and social red taping get eroded.
This is a somewhat far-fetched, politically-slanted review of the movie, but the follow-ups written in commenting on the review are real gems and are worth a read.
The Joker: [speaking to Two-Face] Do I really look like a man with a plan, Harvey? I don't have a plan. The mob has plans, the cops have plans. You know what I am, Harvey? I'm a dog chasing cars. I wouldn't know what to do if I caught one. I just do things. I'm a wrench in the gears. I hate plans. Yours, theirs, everyone's. Maroni has plans. Gordon has plans. Schemers trying to control their worlds. I am not a schemer. I show schemers how pathetic their attempts to control things really are. So when I say that what happened to you and your girlfriend wasn't personal, you know I'm telling the truth. [hands Two-Face a gun]
It's a schemer who put you where you are. You were a schemer. You had plans. Look where it got you. I just did what I do best - I took your plan and turned it on itself. Look what I have done to this city with a few drums of gas and a couple bullets. Nobody panics when the expected people get killed. Nobody panics when things go according to plan, even if the plans are horrifying. If I tell the press that tomorrow a gangbanger will get shot, or a truckload of soldiers will get blown up, nobody panics. But when I say one little old mayor will die, everyone loses their minds! Introduce a little anarchy, you upset the established order, and everything becomes chaos. I am an agent of chaos. And you know the thing about chaos, Harvey? It's fair.
The Joker: You just couldn't let me go could you? This is what happens when an unstoppable force meets an immovable object. You truly are incorruptible aren't you? You won't kill me out of some misplaced sense of self-righteousness, and I won't kill you, because you're just too much fun. I think you and I are destined to do this forever.
Batman: You'll be in a padded cell forever.
The Joker: Maybe we can share one. Then we'll be doubling up the rate this city's inhabitants are losing their minds.
You either die a hero or you live long enough to see yourself become the villain.
Bailango! Feat. Vero Verdier - Asi Se Baila El Tango