I'm honestly not sure why the Blue Bloods characters made cameos in this book. They didn't really seem to forward the plot, and the lore surrounding their world is much different than the lore established for this universe. I felt like overall things could have been explained earlier. It's like de la Cruz was keeping details in order to aide the twist ending, but it just gave us less information about the universe. Additionally, I have no clue what I'm supposed to do with the information/cliffhanger established in the epilogue. All in all, I think the twist ending still would have worked if we knew a little more about the history of the characters earlier. However, at the same time, the prose was much better than Blue Bloods has been lately. I'm hoping the momentum of this series will survive. 
 All in all, it kind of felt like this series was meant for someone like me, who started the Blue Bloods series as a teen, but is now a twenty-something looking for a series with a little more heft to it. I appreciate the effort to make a mainstream, adult fantasy series, and I'm intrigued to see where this will go.