The Dark Knight has placed Batman in the fantastic reality that he deserves. It finally answers the question "If Batman did indeed exist, how would he actually be?" All of Nolan's characters bring justice to the comics. Not the comics of the campy 60's batman, but the comics that went back to batman's roots. The comics of the seventies that started with the revolution of Dennis O'Neill and Neal Adams under the direction of editor Julius Schwartz. Just as they revamped Batman (as well as his villains) into a fantastic reality, a deep and psychological reality, Nolan has done the same with Batman in a different medium.
The Dark Knight is a very complex movie, turning all characters, good and bad alike, into a shade of gray. Batman's boundaries are tested and in no small form. Christian Bale again plays Batman/Bruce Wayne in a brooding and paced manner, whose troubles are easily understood and empathetically felt by the audience. Gary Oldman gives a very raw and real performance as Jim Gordon. Aaron Eckhart stood up as "The White Knight," Harvey Dent.
Heath Ledger deserves every bit of recognition he is getting for this role. He has completely embraced the The Joker as a man "who just wants to watch the world burn." The Joker's humor is supposed to make you laugh and then make you feel bad for laughing, i.e. his magic tricks. The Joker has no boundaries, and in this film, neither does Ledger.
Under the direction of Christopher Nolan, the cast and crew of The Dark Knight have created a masterpiece.