Other reviewers have mentioned the Potter series, but this book reminded me more of Pullman's His Dark Materials trilogy. As in HDM, the world is bleak, the heroes are young and most adults seem oblivious to anyone else, except as they may be used in some grandiose scheme. Unlike with HDM, I couldn't develop any integrated picture of the KTTK world. Things were described, but the descriptions seemed like prop lists. The author seemed capable of throwing in anything or anyone that we might have read about elsewhere. For example, Prometheus shows up - with a different name. At times, I felt like I was reading a screenplay, "Hey, this'll look great in the film, (coming soon to a theater near you) and they probably have some on the backlot!"  Maybe I should have called this 'Will and Dr. Who vs. Screwtape. '  I did want to find out how it turned out, so despite all criticisms, I think it probably works for the early teenager that hasn't already read everything in the genre
The author seemed capable of throwing in anything or anyone that we might have read about elsewhere