The Dark Knight obviously has a "hero" and a villain. But it has its own style that sets it apart from other super hero movies (and other movies for that matter.) I haven't read the comic, but I assume its nature and Mr. Nolan's direction is the reason why. The Dark Knight manages a moral battlefield and a darker atmosphere among the normal super hero dilemmas.
Heath Ledger's performance as the Joker is easily the biggest reason to see this next Batman installment. The Joker consumes every shot he's in, and really creates a brilliantly insane character. That being said, other aspects of the film felt more like after thoughts than anything else, both for their mediocrity individually and relatively.
I appreciated the ride on themes rather than consecutive cheap thrills. The stunts were great, thankfully making rather dull fist fights into something interesting. And the cinematography compounded the good scenes into better ones, and left the mediocre ones as is. Overall, the mood, the themes, and the film as a whole surpassed Batman Begins, but didn't earn itself a place among the "Elite."
The final verdict: watch. The Joker was spectacular. Most of the accompaniment was good. It was very well done, but didn't tap into my style.