The story with Peter adds a nice dimension, since children whose parents are dating each other probably are very ambivalent about each other. Van's hearing loss is well portrayed, and his struggles with understanding speech are explained in a way that will help younger readers understand what it might be like. Having an opera singer as a mother is not something many children have, so that was interesting as well.
Readers who enjoy books where the good and evil sides aren't particularly clear cut, like Colfer's Artemis Fowl series of Delaney's The Last Apprentice will enjoy Van' confusion over whether he should believe Mr. Falbourg's take on the Wish Eaters or Pebble's and the Collector's. I'm still a little torn myself, since Mr. Folbourg is introduced as a kindly, crinkly-eyed older gentleman but at the end manages to disappear, much to Van's dismay. This could be a stand alone title, but I can see the series continuing as well.