1) I don't think I've ever said how much I liked this movie, so I will now: I really liked this movie.

By the way, see it twice. You catch so much more the second time around, and you have time to really absorb things. Spoiler -
Most notably, Rachel's death. The first time, it was so unexpected I was just stunned. The second time, I was crying.
2) Heath Ledger's Joker was amazing. I never really liked the Joker. He always seemed so ridiculous as a super villain, and nothing more than a creepy clown. And not even creepy in a frightening way, just in a "ew" way. (Jack Nicholson's especially! Of course, he's always creepy to me.) Heath Ledger has totally converted me though. His Joker was frightening, insane, disturbing, ingenious, sick, cruel, monstrous, and even funny.
3) I am in the camp that Christian Bale wasn't terrific. His Bruce Wayne was too idiotic, and his Batman too stoic. (I can see what he was trying to do with the hoarse, growled monotone, but it was really less intimidatingly inhuman and more "you should really do something about that cold.") In fact I think his best scene was when Batman actually got angry while beating up the Joker.