This series has always been just an "enjoyable" one for me. Not epic, not wonderful, just "enjoyable". The first one was excellent, with great plot twists. The second was...alright. It wasn't terrible, it wasn't fabulous. 
 I didn't read The Prophet of Yonwood before this one, nor am I planning to due to people apparently hating it. So yeah. I'm probably not going to pick up The Prophet of Yonwood, and will probably only read it when I don't have anything else to read. 
 But this book, the...fourth one, I suppose...it changed everything for me. I loved this book from the very beginning. I could already tell that it was going to be better than The People of Sparks. By the start of the story, the main purpose of the book is established. You know what the characters are trying to achieve. And this is just on technical points! 
 I feel like Doon and Lina really grew in this book. I find myself a little more attached to Doon, because Lina is just so...I don't know. Energetic. Also, even though I don't like science, I find myself a little more similar to Doon than to Lina. 
 I think all of the characters in previous books got very developed in this one, and even the new characters here got developed as well. Even though all of the new characters are basically from just one family and nothing more. 
 Possibly the only issue I have with the characters is Lizzie. Lizzie is just too boy-crazy, for a 13-year-old, and I can't honestly picture her and Lina being friends. In the first book, Lizzie was Looper's girlfriend. In the second, she was very attached to Tick. And in this book, we get some parts in her perspective, and we find that she's now looking at Doon (and later on, Scawgo). I feel that DuPrau could have maybe developed her character a little bit more, but I guess that's alright. 
 Torren was pretty annoying too. And I genuinely liked Kenny's character. 
 There aren't many plot twists in this book, but there are plenty of wonderful realizations coming from the characters, especially Doon and Lina regarding the diamond. Also, the lack of plot twists are made up with just a few more doses of action. 
 With this book, I have realized that DuPrau actually is very good at writing action. Why she seems to avoid it in this series, I don't know. But her action scenes are so quick, vivid, and frightening. In fact, I read a whole chapter in what felt like five minutes, simply because of all the action. 
 The writing was very descriptive but I hardly felt very lost in it at all. It was simple to understand, and really described everything well. 
 The pacing was quick, and the adventure is underway when you're, like, 20% through the book. Compare that to People of Sparks, where the journey started at around the halfway mark of the book. 
 The worldbuilding I felt could have been more improved, but we get to see more villages and how they're taking the dead world. We also get to see more roamers and learn more about the catastrophe. But maybe I'll be satisfied with Prophet of Yonwood. If I had read it. 
 This book was more than just enjoyable. It was wonderful, and I'm glad to have liked it so much. 
 Also, this is the first series I began and finished in 2015. 
 Maybe I should start finishing more series. 
 My review of The People of Sparks