I didn't like it - the writing to me felt like someone trying to copy Miller's style and falling pretty far short. Batman's characterisation is horrible and makes him feel more like a Sin City character. The treatment of Robin, and other characters such as The Martian Manhunter, was silly and self-indulgent.
There were some scenes I liked - some interesting use of the Flash, The Atom, and Captain Marvel (his death scene was great). And I loved that creepy bit with the weird, wide-eyed character in Saturn Girl's outfit.