The dark knight

Its dark for sure. It plays out like a shakespeare tragedy.
Writing a superhero franchise is never easy. Hero has to win in the end. Villain will have to fail. Heroine should still swoon over the hero. There is not much creative freedom. You cannot disturb the status quo. You have to preserve the legend and all associated characters.
But Nolan explores the darkness of the human mind beautifully even between this. Its sad, scary, tragic and brilliant. Nolan will now face the difficulty of making a bigger villain in batman 3 after pushing limits giving life to Joker.
In the end Batman is someone you feel sorry for, not one you want to be. He is prisoner of his own destiny.
As Dent says in the movie,' if a hero survives long enough he becomes a villain.'