
As you may recall from my review of Angelology, one of my pet peeves is literary authors who tackle genre fiction as if they're slumming. Book critic pretensions to the contrary, literary fiction is just another genre -- some people like it, I don't particularly unless there's a darn good story attached, but there is an unfortunate perception that it's automatically more sophisticated writing and more worthy of respect than "genre" fiction that features detectives, spaceships, or monsters.
Still, a literary author can do genre fiction well if s/he brings with him/her a love of the genre. Lev Grossman brought a very sharp knife. He took Harry Potter and the Chronicles of Narnia, slashed their wrists, put them in a nice warm tub, and said, "Isn't this pretty and grim?"
( My pretty grim review of The Magicians, with mild spoilers )