I really liked this book, even though it is VERY different from Gail Carson Levine's other books. First and foremost, it is actually set in our world, in a school in fact. Usually, I would have stayed away from a book about a school, but considering the author and the promise of fantastic elements, I decided to try it.
I am SO glad that I did. This book in FANTASTIC!!! Unlike most realistic fiction, it never preaches about how terrible cliques and popular people and high school are. Instead, it shows a point of view that is NEVER shown: what it's like inside a clique, and the idea that popular people really DO have the capacity to be nice. I mean, if you want to complain about card-board cutout villains, read a normal realistic fiction book.
There was only one really 1-D character in the book, but this added to the realism; I've met a few people who really act like that. Besides, all the other characters were wonderful, so it didn't really matter.
Wilma, in most aspects, was a good character. I especially loved the way she managed to pull unpopular people into the group without making it seem forced, which is no easy task. The only thing that seemed slightly odd was the romance, but that was just because of the age. It would have worked better if this had been set in highschool, but given the nature of the wish Wilma makes, that wasn't possible.
A certain part of the wish was the only problem in the book; from my point of view, the catch in it seemed rather obvious. But then, I read WAY too much fantasy, and therefore probably understand "watch what you wish for" better than Wilma did. Besides, it wasn't a very big problem, and given that Wilma took two seconds to think about the wish before she made it, it can easily be ignored.
If you like fantasy or realistic fiction, you HAVE to read this book.