If you want to read about the plot, read the jacket copy. :)
Excellent world building and even better characterization.
Written in alternating voices - Elias and Laia. Though the chapters are headed by the characters' names, they don't need to be. The voices are distinct and the plot events unique to the individuals. Because the book is written with both characters' voices, I felt that I got to know each of them as individuals.
As I read, I did want to know more about several supporting characters. Surely the Commandant couldn't be as cold and evil as she seemed? Her back story is hinted at late in the book. Perhaps we will see more nuance in her personality in future volumes.
Where the power of Red Queen (Aveyard) is in the issues raised in the sociopolitical context of the people's powers, the power of this book lies in the compelling emotions of the characters.
Laia constantly compares herself to her now-dead parents, feeling herself lacking. Instead, as the story progresses, she begins to understand her own personality, while different, is also strong. Early in the book, she puts her own survival above that of others, taking the gifts they offer; later she recognizes her power to help others, surprising many along the way.
I eagerly await the sequel in April.