I honestly didn't think it was that bad. Great build up to Joker's big reveal, IMO. I loved the shots of Chicago (the opening shot especially), and the zom in on Ledger just standing at the side walk pretty much let you know that this guy means serious business.
The dialogue? It did it's purpose, and it's the kind of thing youd expect to here from half wits who rob banks for a living. Anything in there to make 'em sound smart would just been ridiculous (if they're really that smart then why wouldn't they just host their own robber instead of working for someone else?).
The Goon's performances? I liked them. They acted like goon's should act. The roles don't demand anything super-special amazing from them, they just need to act like tough SOBs. I think anyone expecting Oscar-worthy work from henchmen may need to re-think who the movie centers around. Oh, and please, don't make fun of their voices. That's probably exactly how they sound like in this Batman universe. How would YOU like it if people made fun of the way you sounded and said you sound too old fashion? Exactly. It's the voices they were born with and the have every right in the world to talk with them.
Fichtner? Awesome, IMO. Calmly taking off his glasses, blasting goons with his shotgun. Pretty badass. And yes, I have no problem with his end line. To me, it sounded like he got shot in the lung. He probably couldn't breath and was desperatey trying to catch his breath *while* talking smack to Joker as well. Now there's a REAL man.
The physical comedy? How could anyone NOT like it? Only Joker could pull off such a crime as it played out. The timing of the bus(es) was just great.
And finally...like people said up above, "The Joker" just blends in with the rest of the dialogue. I honestly don't notice that. I'm too involved in the awesomeness of this scene.
Oh, and the music in the background...nice touch, Nolan. Really awesome.