My DS got Kingdom Keepers as a Christmas present from my sister. He read it twice, and I read it- now my other DS who is 7 is reading it.
It's a great book, lots of imagination went into writing it.
My DS enjoyed it so much he is going to read Peter and the Starcatchers next, which is also written by Ridley Pierson (sp?) That author just got a new loyal fan in my DS.