The Knight grows darker in response to Evil's manic push to the very edge. Although there is no direct view of the most intensely violent acts in this movie, the viewer feels every bit of the menace that is there in those acts. Evil can create nothing - only twist and degrade good. The Joker embodies the complete degradation of good in a human. The Batman responds by super-heroically absorbing The Joke's evil, deflecting it from Gotham. This is a breathtaking movie, not great "fun" to watch, but as useful as the best sermon about Good and Evil for instructing us.
Best Comic Book movie ever made. Pay attention, though. Genre used as a platform to inspect very important social issues. My understanding is this has always been a primary purpose of comic books. I'm not a comic afficianada, but know lots of smart geeky boys who like to "school" me. The world of COMICS and the world of TOPICAL REALITY are blended in a subtle dance. You have to be as smart as Favreau to catch this. If you're not as smart as Favreau, one of two things will happen: 1) you will enjoy the movie immensely; 2) you will write a review that complains that the movie is slow in parts, or unrealistic about the Mideast or some other nonsense like that. Bottom line: Go see the movie. Treasure everything, every moment, every line. I live for 2010.