Honestly, I give it a 6/10.
Batman isn't supposed to be realistic, so I don't know why Nolan is trying to portray him as this.
Ledger's Joker is MEH. His look didn't help either thanks to Nolan's "realism," and the fact that his dialog was terrible. How many times do we have to hear "do you know how I got these scars?"
The movie took too much from TOO many comics, and jumbled it into one.
Sorry to whoever did the screenplay, but YOU do not know Batman. In fact, I'm tired of these new Batman stories. I wish to have a comic story without Hollywood added crap.
I could make the real "The Dark Knight Returns" using the exact Miller story, and not changing one bit, and casting Michael Ironside as Batman, and Daniel Day Lewis as The Joker. Yes, I know there are other heroes, and villains in the story, I did not forget about them.
Harvey's rise to insanity was stupid, bar none. Who wrote this crap? Also, Joker's plans of always getting away made no sense. It's not The Joker at all. Well, this is after we knew he was wearing make-up, and was just a kid who got beat up by his dad too much apparently.
The movie dragged on too much. Did you want to hear the story of how the story dragged on too much?
EDIT: I forgot the GCN scene with the guy who wanted Joker to get killed. I was thinking, damn, they took this from TDKR, I can't wait to see The Joker on tv, and telling everyone in the audience their going to die, and all have happy faces. Oh wait, we didn't get that. We got more bomb threats.