At the beginning I was rather enjoying this book. The central premise of siblings on either side of a war was interesting, the Slavic-influenced setting appealed to me and I liked the writing in the first few chapters. 

Unfortunately the characters ultimately ruined the book for me. Almost all the characters felt underdeveloped, especially Sebastian whose arc over the course of the book felt rushed and unconvincing. Most of the characters were also distinctly unlikeabe (particularly by two thirds of the way into the book) and I struggled to really care about what happened to any of them. 

Overall the book was okay, it was generally entertaining and had some interesting worldbuilding, but I won't be reading book two.