I really enjoyed this book! I think this book might be more appealing to people who like math and/or literature because it involves some math and literature puzzles that you can either solve yourself or wait for the characters to solve. I think this book is good for kids 9 and up. This book has some good humor, but i think it would a.) make more sense to girls and b.) it is more oriented to girls making me feel that this book would be better for girls. There is a boy in it, but he is not a main character, as this is about girls at a private school, and it makes you feel that way (you are at a private school for girls only, that is). The girls have healthy relations (none of them is a big boss of ANY, or all of the other girls) and get along well, except for one point in the book where Sophie (one of the girls) jumps to conclusions, other then that they get along great!