There are cats, and Greek gods, and doors in Bigdale, and kids who play soccer and kids who wouldn't dream of playing soccer; there are wise grandmothers who can't fix everything but are awfully good to have anyway; there are creepy teachers and best friends who need saving.
It is good fun. You should read it. Also, while it indicates that it is the first in the Cronus Chronicles, they're not the kind of chronicles where it's multiple volumes of one story: this story has an ending. Also a beginning and a middle, in some order. It's not one of those series books where you have to read the next book to figure out whether the story works or not. The next book will be a different story. I'll be excited to read that one, too.
(Local baseball fans may know Anne as Batgirl, the source of bat_girl_twins, the best baseball blog in the area -- or at least the only one I bother to read. While there's no baseball in The Shadow Thieves, Batgirl's sense of humor comes right on through.)