Actually, BB was really very good movie and I doubt Ledger is one of actors, who do this. Besides, I also can understand why you are so negative about this interview, and you know why? Because you don't like everything, what has any connection with BB. Isn't this tuth?
No, no! BB had one thing, which didn't have other superhero movie. It had much bigger speculation of psychological aspect in the movie. Besides, it had excellent cast and very good storytelling. At nowadays, you can find hundreds of people, who can say that BB was one of the best movies in it's genre aka superhero/comick book movie. Just look at other superhero movies. They didn't have this.
Well, as I said, there are more bad than good comic book movies. BTW, he explained why he doesn't like comic book movies. And you know why? Because of predictable and boring storytelling, which didn't have BB.
Yep, but the difference is in Nolan. He is one of directors, who do what they say. The same can go to Ledger and his take on the role (A Clockwork Orange Joker? Hell Yeah!

).