I really wanted to like this book more than I did. And some parts, I truly loved. The magic system and the world building are great. The characters and the story, however, didn't pull me in the way I was hoping.
I didn't realize until much, much later that this book is a spin off of another series. A lot of this book talks about Yelena and all the wonderful, heroic things she has done, and not knowing this was a spin off of Yelena's story, I kept growing annoyed with all the talk about Yelena. This was supposed to be Opal's story, but half of it feels like Opal telling the reader about Yelena's story.
Another thing that made it difficult to really get into this book (I mean, look how long it took me to read this -- nearly a month, which is a looong time, for me) was that I never did pin down the plot. There were a lot of mini plots/quests, but nothing over all that made me invested in following Opal's journey.
Perhaps things will be made clearer in future books of the series, but being that I couldn't truly get into this one, I doubt I'll continue reading this series.