I saw the movie twice. I happened to think that this maybe the best comic book movie ever done and it is certainly the best Batman movie ever done.
What made this movie for me was the defining of Batman as a protector of Gotham and he is willing to do whatever it takes and be whatever type of thing Gotham needs him to be in order to make Gotham a better place. A hero to me has always been someone willing to do the right thing no matter what it costs, even if it costs you.
I know that Ledger did a great job with the Joker, but it is more important to me that this be a good movie about Batman.
To be totally cold sounding Ledger dying was a horrible and tragic loss for his family and for movies, for the franchise of Batman it was probably a blessing. Ledger did the best Joker ever on screen (large or small) and probably has helped DC in making the Joker truly dangerous again. If Ledger had not died the marketing people would have said to have a round 2 with Batman versus the Joker and that would have caused the franchise to become stagnant on only the third film, which is almost always the worse one in many franchises (Aliens 3, X-Men 3, Spider-Man 3 and Terminator 3 come to mind).
Another big plus was Two-Face used so judiciously as to be perfect. All the other movies go overboard in using the villains way too much and having fun with all these great bad guys and they lose giving the movie any plot whatsoever.
Some other highlights, Batman destroying the big brother machine, the people on the ferry boats refusing to kill each other, Jim Gordon, Alfred burning Rachel's note, Bale being a good Batman and a good Bruce Wayne.
I think this movie rose above being a comic movie and was a good movie, possibly a great movie and certainly a great comic book movie.
PS - This post is for Matthew.