The Dark Knight is a great movie, but it's not a great comic-book movie, because it's very grounded and lacks the hallmarks of Batman.
There's no Batcave, the "Batmobile" isn't bat-themed (and it gets destroyed and replaced by a bike that also isn't bat-themed), Batman doesn't use his grappling hook once in the entire movie, Batman foregoes the cowl for a helmet, Batman doesn't crouch and scowl, Batman doesn't lurk in shadows, and Batman exists in a world with no supernatural entities. All of the signature characteristics of Batman are stripped away; hence, rather than being a Batman movie, The Dark Knight is a generic psychological thriller that happens to have a "rendition" of Batman in it.
I like the movie a lot, but it's obvious that Nolan wanted to get the Batman themes out of the way in Batman Begins, so that he didn't have to deal with them in The Dark Knight. He literally blew up Wayne Manor and the Batcave at the end of Batman Begins.