I read this book in a couple of days after I finished the first one, because I was intrigued. You can look up the book here.
Summary: The People of Sparks finds the citizens of Ember wandering around the new world. They come across a mysterious town called Sparks. The people of Sparks agree to take the Emberites in and give them food on the condition that they help work. Lina, Mrs. Murdo, and Poppy stay with the town’s doctor, as Poppy is ill. Doon, however, goes to live in an old hotel with the remainder of the Emberites. Tensions soon rise among the two groups, and conflict threatens to tear the town of Sparks apart.
Likes: I liked this book. It revealed more about the mythology and history of the world of Ember, and also dealt a lot with themes of nonviolence. It demonstrated a lot about human nature in the face of conflict.
Dislikes: Parts of the book felt a little preachy and contrived at times, because the author was so intent on getting across her message of nonviolence.
TL;DR: I would recommend The People of Sparks to anyone who likes dystopian fiction, is interested in YA fiction, or has read The City of Ember.