Yeah, the film dips significantly when he's not onscreen, the same way The Godfather sort of wanes when Brando's absent. But Brando's is a great performance in a fine ensemble; Ledger's the star attraction in a weak pool. And I see no reason why his performance must be put on the same platform as Brando ahead of every other great acting display out there, much less a year after Daniel Day-Lewis's performance in There Will Be Blood - that pretty much obliterates everything around him.

There's more to The Dark Knight than Ledger's performance though. It aspires to social relevance, to political realism, to psychological plausibility; none of which can possibly be achieved in the fictional city of Gotham. In order to achieve any of those three things, you'd have to change the fundamental elements - ie. an urban environment in which the high levels of crime are in flux with all other social and economic factors leading to it; also, a hero who doesn't dress as a bat as a result of violently being orphaned as a boy.

I've read my fair share of critical writing on it; it didn't make Sight & Sound's top ten, but a few contributing critics have it in their personal top five (January issue). Again, their reasons aren't convincing enough for me; they find great enjoyment in the film but either ignore or fail to notice its (reactionary) political ideologies or self-defeating 'artistic' intentions (which arise from commercial needs, not artistic ones). Ebert loves it, of course - never a good sign.

But all the praise amounts to vague buzz-phrases. The film could have been amazingly fun, but it shoots itself in the foot with all the "omg anarchy is evil" bullshit. It's empty, artistic dishonesty.

There's a fuller discussion here, from which much of my opinions on the film stem.