This was a cute book with a good mystery element and a pretty original idea. I can't say I've every really heard of a book about a Nightmare before. Like an actually human-ish Nightmare person. I think the basic ideas of how all of the magic worked was really well explained, though a little bit more character development especially with the secondary characters would have been nice, but I did enjoy what was shown of them. As for the mystery element of it, i'd say it was pretty well thought out. I guessed at least seventy percent of it before the big reveal, but there was still some shock factor there. Overall though I really enjoyed this book.