Firstly, Azzarello isn't a limited writer. Have you read the 100 Bullets series? A masterwork which he deservedly got awarded for.
Yes, 100 Bullets is a masterpiece, it is fantastic. You seem to think I said Azzarello was a bad writer, I only said he was limited. He is a great writer, but he can't go very far at all outside a grim'n'gritty setting, that's what I meant.
And what characters were reduced to cardboard cut outs?
The joker for the most part of it. I don't consider one-off panels with him crying equivelant to depth. It had a lot of potential, but seemed to be wasted, but admittingly was good. Very fortunately, his final scene with Batman redeemed it a lot.
And yes, Johnny was meant to be a DC reader, very clever if his monologue wasn't just a constant stream of Joker praise followed by fear. Joker could've been a brilliant story had Johnny been more developed more, as well as Joker coming off more than just a violent thug. I'm pokay with a violent thug Joker appproach, but it really didn't work when the main driving point was how charismatic he was meant to be. A better treatment would've pulled the rug from under our feet later.
There was also too much really unnecessary and random tidbits. Joker raping Johnny's wife under the supposed context of "he raped my trust" is really odd, considering it's really "broke my trust", and therefore should've broken his wife's arm or something. The throwaway comment about Two-Face being a bigamist just came out of nowhere and vanished just as quickly, which needed either explanation, or cutting. The old people getting murdered by the joker is also a really poor writer's trick to get the readers to se the villain is really bad too.
That said, I was a bit harsh in my earlier comment, I always reply biased to a biased comment. I loved how Croc was portrayed here too. But overall the story is disappointing, a mediocre book that many (not you) think to be great simply because it is rather "mature" (And I use that word in the loosest of senses).