Best comic book/graphic novel and best superhero movie ever. No question.
The opening bank robbery scene is one of my favorite scenes from any film ever. It is so well done and well written. Plus, Ledger's Joker is revealed for the first time and its glorious.
The Joker's magic trick where he makes the pencil "disappear" is just as epic now as it was when I saw it in the theaters and everyone yelled "OHHH!". His "tryouts" later on are just as insane as well.
Furthermore, the tunnel chase and the 18-wheeler flip are so intense and so fucking awesome.
The interrogation scene between Batman and the Joker is the fulcrum on which the entire film balances, as Nolan points out. It displays the Joker's adamance towards his cause, the lack of real power on Batman's part, and the Joker's power over Batman. Batman refuses to break his code but does go so far as to torture the Joker--the Joker prodded and pushed Batman and he crumbled under the pressure.
Everything about Ledger is fantastic. The constant lip licking, shifty eyes, and every other mannerism. Plus, the way he delivers his lines is superb. Recognition must go to Nolan and the costume people as well for "designing" a Joker unlike any other that we've seen in terms of looks. Ledger's hair and make up is ratty and tattered, unlike the relatively clean Jack Nicholson version.
I wish this thing was longer than 2.5 hours. It's that good.