The fourth and final installment of DuProu's Ember series, I felt The Diamond of Darkhold fell just a teeny bit short. Everything had a nice happy ending, including an awkwardly told, unchronological almost-epilogue. It vaguely had a tie in with Prophet of Yonwood summarized in one sentence. And everything was just so easy. She really could have stopped at People of Sparks, yet she still leaves this open for continuation.
Those minor complaints aside, I enjoyed this book. It was a nice denouement for the series, yet wasn't quite as thrilling as the others. Parts of it were clever and unpredictable, and it was rather enjoyable. What I really would like to read is about the first people to go to Ember, which would tie in Prophet of Yonwood much better in my opinion. As a series, I'm not sure this one is a winner. I don't feel my time was wasted, but there are other YA authors in this vein (Haddix, Lowry) who I would suggest first.