I like the idea of the reversal, I just wish it had been ... I don't know, developed a bit more. For me there were too many unanswered questions that were left dangling, such as when/how the second daughter was conceived and why the girls were physically identical. I think it wouldn't have bothered me as much if there'd been a bit more explanation.

On the other hand, I think I would've been more happy with this book if I'd picked it up with no knowledge of the others -- it just felt a bit weak to me compared to the rest of the books in the series. It wasn't terrible, it just didn't feel up to the standards of the other ones. Maybe I'll like it better on the re-read.