Definitely the best Batman movie ever, had a great story and great writing, and a joker who really served the character in the comic books well.
The one thing I would change if I could would be to go ahead and show the graphic bits and let it be R-rated. I think the MPAA tripped this movie up, like they trip up every action movie that wants to stay in the PG-13 slot.
After seeing The Dark Knight I asked everyone, "Why so serious?"
My father was...a drinker, and one night when he was especially crazy. My mother grabbed a kitchen knife, and daddy didn't like that. No, not at all. He took the knife, and started cutting up her face, laughing the whole time. After he's done, he looks at me and says, "Why so Serious?"