If you’re looking for a book similar to other titles by Margaret Peterson Haddix, then Palace of Mirrors may not be what you are looking for. Unlike Among the Hidden and the other books in the Shadow Children series which are futuristic and political, Palace of Mirrors takes place in a medieval/fantasy setting.
Although I found that this book started slow, the story of a peasant girl who is raised believing that she is the “True Princess” develops interesting twists when the conflict heats up in the second half of the book. Girl readers in upper elementary and middle school will enjoy the turn of events which Cecelia, the main character, encounters.
Although I think most readers will read this book for its entertainment value, the dialogue between Cecelia and Harper, her best friend, about making choices vs. following your destiny could generate interesting discussions. In addition, girl readers will enjoy the power that Haddix gives to her main character.

Ah you are venturing into fantasy. Something I rarely do.
Ah you are venturing into fantasy. Something I rarely do.