I recently saw "The Dark Night," and in short, I found the movie to be quite enjoyable. However, you need to be in the right mood to see it. Let me explain. (Note that I did not see Batman Begins and so this may be redundant for those who did.)
The entire movie is very dark and dreary. It is not one of those uplifting movies where you emerge feeling refreshed and happy. Instead you emerge feeling the stark challenges of Gotham City and the end itself will leave you pondering. (I am not going to give the end away, but it was certainly not what I expected.)
In terms of the characters, Christian Bale reprised his role as Batman. He was good in the role, but I was less impressed with him as I was with Heath Ledger. Ledger was great as the Joker. He did a great job capturing the outrageous craziness of the Joker. The character is meant to border on insane. Ledger played the role to the tee infusing a sense of completely insanity combined with a deep intelligence that was the joker.
The heaviness and crime ridden nature of Gotham City are the center piece of the film. The film pulls you into the situation in Gotham City. On more than one occasion, I felt myself overcome with revulsion for the joker and at the same time, recognizing the helplessness of the citizens of Gotham.
In summary, the movie was very good. It definitely works hard at infusing the dark despair of Gotham into the film and IMO, it works. There is lots of action and explosions, but the general plot is much deeper than that with the whole good vs. evil thing going on. I will close this short review with a quote from the movie:
You either die a hero or live long enough to see yourself become the villain.