I think Heath Ledger's interpretation of The Joker is going to become the standard for the character in the future, who "totally new"?
I think not.
Which is not to take away from Ledger's remarkable performance -- and he was the best thing in the picture.
But it also speaks volumes that this film only confirms Adam West was the best Batman ever. The Bats character is a total non-entity in all the post-modern versions of the story; West's Batman was loopy, obtuse, and over the top, but dang if he wasn't interesting to watch all on his own.
Somebody really needs to do a YouTube mash-up pitting Ledger's Joker against West's Batman.
THE DARK KNIGHT is one of the best superhero films ever, but as a movie it's akin to Sergio Leone's Dollar Westerns or John Woo's Hong Kong action films. Visually eye catching, opportunities for bravura performances, some nods to Things Of Importance, but nothing that can sustain detailed analysis. It's a good movie and grand entertainment, but it's a YOJIMBO, not a SEVEN SAMURAI.
I don't think the superhero genre can sustain a SEVEN SAMURAI (for those slow on the uptake, yes, one can make a movie about seven superheroes banding together to save a city; JAWS is about guys on a boat chasing a big white fish but that doesn't make it MOBY-DICK). I think the inherent absurdities of the genre (and mind you, those inherent absurdities are what makes it appealing) limit the range.
I may be wrong. But I think the superhero genre only works when it winks at the audience in the manner of the earliest Bond films and says, "Yes, we all know this is nonsense, but isn't it such glorious nonsense?" For all it's grandiose superstructure, the foundations are not that strong.