I guess we all knew that there will be another installment of the trilogy when we watched The Dark Knight. Or at least, we hoped for it. And i think it is the main problem of such movies, since despite their qualities you perceive them as an interlude to the grand finale.

As far as the atmosphere is concerned, the same gritty feeling of Batman Begins is there. The tempo with which the characters, both heroes and the villains, have been introduced makes The Dark Knight rather a drama than a comic book brought to screen.

I guess the decision of the authors has been to create something monumental and they've been successful in that, especially if you consider the running time.