For me it's Nolan's Two-Face - he's my favourite Bat-villain, and he was portrayed perfectly. I don't buy into all this he-was-already-damaged crap, and seeing such a nice bloke get flipped over the edge was superb.
But I'll be honest, Nolan didn't really screw any of the characters over. And Cillian Murphy - what a genius bit of casting - IN ALL THREE!!!!