I thought I'd mention that I did see The Dark Knight over the weekend. Without spoiling anything, I can tell you that is an excellent movie, but it is definitely very dark.
OK, potential spoilers from here on.
This movie is definitely The Empire Strikes Back of the new Batman franchise. It's arguably a victory for the good guys, but the price is very high.
This movie is also extremely disturbing. It's not quite torture porn, but the Joker brings very much the same kind of sick, sadistic vibe to the picture. The Joker is not funny or slapstick -- he's a nihilistic killer, pure and unadulterated. He's homicidally insane, and he wants to take everybody he doesn't kill down to his level. Heath Ledger pulled off the role exquisitely, but I can see where just portraying this kind of psychopath might make a guy a little crazy.
There are some great lines in this movie, too. I think the one that may have moved me the most was this one: "Give that to me, and I'll do what you should have done ten minutes ago." You'll understand when you see it.