I think this is one of my most frustrating and favorite books. Yelena is a great character who grows and makes mistakes and learns from them. She does what needs to be done. The romance between her and Valek does not overshadow the rest of the book and it does not overshadow her decisions. Such a contrast from most YA books nowadays. 
 Ari and Janco could have had a bigger part in this story, only because I really do love them! And a part of me still wishes for a book 4 where the Commander's story could be more fully explored. 
 That said this book is an excellent conclusion to the series. And if you can make it through the parts where Everything Goes Wrong, and then that part where It Goes More Wrong, it's worth the read.