Batman is well-portrayed here - far too many writers fall into the trap of 'Batman never smiles. Period.' More accurate would be 'Batman never smiles unless he knows you very, very well.' Which, functionally, means his smiles are basically restricted to Robin, Alfred, Batgirl, Catwoman on occasion, and the occasional upward twitch of the facial muscles when dealing with the Joker - because, like it or not, they DO know each other very well indeed.