I found this book much more enjoyable than the other two reviewers. I was fairly cynical at the beginning, but this is more than a reworking of Lord of the Flies. Although the author could have created an absolute dystopia involving the behaviour of the girls, I feel it works well. There is cruelty and unhappiness but in my opinion, it is suitably realistic. Girls are cruel, but they are also intelligent and have the ability to co-operate.
I enjoyed the narrative style, although at times it does have a certain gimmicky quality to it, it is not without irony and humour. This saves it from becoming too focussed on breaking the style of the linear narrative and keeps to the story.
What spoils the book for me is the ending. I understand what the author is trying to portray and her intentions, but it didn't quite work for me.
I'd certainly recommend this to older teens - who will certainly recognise their own and their friends' behaviour here and also to young women who will be glad that they are long past some of the things younger girls do!