I was cleaved in two by the grief at the beginning of this. One of the most poignant displays of loss and healing and I am still heartbroken about it. 
The jumps back and forth in perspective got a little tiring at the end but only because I *really needed to know what happened.* 
Zoya and Nina carried the plot, imo, but both of their journeys were wonderful. 
I went full WTF at the end. Cannot wait to dive into Rule of Wolves.