We had a huge fight on this matter on Bug the other day so thought I'll bring piece of it here on TFF.

Nolan's a lot more faithful to original source, he used every ounce of Year One comics in Batman Begins alone, along with it his movies are, if this can be said for comic book movies, realistic and more believable.

What I like most about Nolan movies, he gave equal attention to both Bruce Wayne and his alter ego, something Burton failed to do. Lastly, probably the biggest comparison out there, I prefer Nolan's Joker, Heath Ledger's performance overall. A far more intelligent Joker, one that threats everything as a game and goes into as if he has nothing to lose, thus out of two Jokers more dangerous opponent.