Every part of "The Dark Knight" is perfect.
Every part.
Transcending the "comic book movie" genre with ease, the sequel to "Batman Begins" soars on leathery wings into the realm of the best films ever made. There is no one word to describe it. It is indeed dark, as it is complicated, disturbing, and exhilarating. It not only faithfully adapts source material which has endured for nearly 70 years - it in some cases improves upon the material.
Before we start, let's review that material, the classic, mythic players involved:

Bruce Wayne/Batman (Christian Bale) - After seeing his parents killed before him, billionaire Bruce Wayne decided to dedicate his life to eradicating the criminal element which thrives in his home city of Gotham as a masked crusader of the night. Christian Bale is probably the best actor you could pick, alive or dead, to fill both the kevlar suit of Batman and the three-piece suit of his playboy alter-ego.

The Joker (Heath Ledger) - A psychotic, mad-dog killer with a permanent smile cut into his face who wears "war paint" to frighten his enemies. Another perfect choice, it seems, as Ledger demonstrates how truly horrifying the Joker is as a force of what might be called pure evil. Ledger drips creepy in every Goddamn scene - his performance has to be seen to be believed.

Harvey Dent (Aaron Eckhart) - Gotham's new District Attorney, a knight in shining armor whose passion for justice begins to lean towards a murderous obsession.

Rachel Dawes (Maggie Gyllenhaal) - The love of Bruce Wayne's life, who can never be his as long as he dons the cape and cowl. She fights crime as a prosecutor alongside her new beau Dent in the courtroom.

James Gordon (Gary Oldman) - A lieutenant within the terminally corrupt Gotham City Police Department, Gordon has struck up a clandestine partnership with the officially illegal vigilante, Batman.

With this cast of complex, very real characters, Writer/Director Christopher Nolan weaves a tragic tale about crime, about truth, about heroes, about the existence of basic good in people and what it takes to erase it.
Now, as the Joker would say: Here... we... go.

"The Dark Knight" opens where its predecessor left off: Batman and the GCPD under Gordon are doing their best to rid Gotham of its obstinate mob presence. Meanwhile, two new forces are confronting crime in the city head-on: dimple-chinned DA Harvey Dent and the lethal Joker, who inspires nervous laughter throughout by perpetrating shocking acts of abominable violence.
The Joker recognizes the grip of terror Batman has on organized crime; after all, vigilantes have no jurisdiction. But as I'm sure you're aware from seeing the trailers, he has a solution: Kill the Batman.
And so he begins a reign of terror, explaining to the public that he will begin killing people every day until the Batman takes off his mask. He begins by torturing and killing one of many Bat-imitators which have popped up in the city on video.
Next he offs the judge in a landmark trial Dent was spearheading, and on the same night kills the chief of police. Bruce Wayne can only watch as the Joker next attempts to assassinate the mayor of Gotham. Gordon takes the bullet for the mayor and is killed.
Public reaction is now overwhelmingly anti-Batman, and Wayne prepares to turn himself in. Instead, Dent holds a press conference to admit he is Batman, turning himself in. His plan is to lure the Joker into a trap wherein Batman can take him out once and for all.
The plan works, more or less, and it is revealed that Gordon faked his death in order to protect his family. He arrests the Joker and the mayor announces Gordon will be promoted to Commissioner.
The movie could end right there. But like a three-hour session of tantric sex, it doesn't. Because if you're even vaguely familiar with "Batman" comics, you'll know one thing: the Joker always escapes.
Gordon is alerted that both Harvey and Rachel never made it home that night, so he lets Batman... ask the Joker a few questions. After an especially brutal scene (which is saying a lot for this movie), Batman gets the locations of the two attorneys, who have been tied up and rigged to bombs. Batman sets out to rescue Rachel, but instead he finds Dent as the Joker triggers the bombs with his one phone call from jail.
Rachel is killed, and half of Dent's face is burned beyond recognition.
The Joker gets away.
The Green Goblin once said "Only fools are heroes... Because you never know when some lunatic will come along with a sadistic choice." Well the Joker would eat the Goblin's intestines for breakfast.
By this point in the movie I was beginning to finally realize just how epic a film "The Dark Knight" is. WIth every passing moment, I was more amazed. I lost count of the times I said "Oh my God" out loud.
First the Joker calls in to a talking heads show where a prying Wayne employee is about to reveal Batman's identity. The mass murderer announces that unless some citizen of Gotham kills the Wayne employee within an hour, a hospital will be blown up.
The employee survives the hour (barely) and the Joker makes good on his word, demolishing an evacuated Gotham General Hospital. In a truly bizarre scene, he releases Dent and tells the newly christened Two-Face to enact revenge on those Dent feels were "responsible" for Rachel's death.
The Joker then declares his dominion over a Gotham petrified with fear, and announces that those who don't leave it by nightfall will be his subjects. In the course of a mass evacuation, he plants bombs on two ferries leaving the island, one full of convicts and the other of innocents, leaving triggers for the ship captains to destroy the other vessel and save their own lives. Batman arrives and fights his way up a skyscraper, through clown henchmen and SWAT alike, to do battle with the Joker one final time. His nemesis gloats that the veneer of civilization means nothing to people when their lives are at stake.
In the end neither ship is willing to kill the other. But the defeated Joker admits his real victory will be the destruction of Gotham's spirit through his corruption of Harvey Dent.
Batman speeds to the place where Rachel died and finds Dent holding Gordon and his family hostage, preparing to execute Gordon's son. Batman stops him in time, throwing himself and Dent out of the building, apparently killing his former ally.
Batman and Gordon agree they cannot let the people of Gotham know what happened to their heroic DA, their White Knight. Batman proposes to take the blame for the murders Dent committed, in order to let the people of his city keep a hero they can believe in. Gordon reluctantly agrees and calls in a manhunt on the vigilante, who flees into the shadows.
When Gordon's son asks his father why Batman should have to run when he has done nothing wrong, Gordon responds, "Because he's the real hero... A Dark Knight."

Okay, so take a breath.
"The Dark Knight" met and surpassed any expectations I had for the film, even though I had built up those expectations pretty high. Hell, even the music grew on me - the Joker's theme is another perfect facet, by the way.
The question I can't quite answer is whether or not it's the best comic book movie ever. I believe an overwhelming consensus would be "yes," and I have trouble disagreeing. You can certainly comment on this review (if you ever finish reading it) and tell me what you think. But the truth is, Christopher Nolan set out with to make "realistic" comic book films, and I can say with some certainty that he succeeded with this one, because it convincingly presents the true tragedy of Batman's compulsory war on crime, a war he can never win all the way, especially after the casualties it has sustained. The film is filled with heartbreaking moments, a few of which I'm not even going to list here.
It will leave you drained - it is a long movie, there's no doubt. But in a way, I think comic fans have been waiting for this movie their entire lives. This may be the last chance we have to peer in to Nolan and Bale's Gotham City. So take a good look. "The Dark Knight" will never be topped.

Grade: A+ (duh)