I'm not normally fond of 1st person narration because I find it often not done well. Mark Stone knows how to do 1st person, and I enjoyed the quirk that he used 1st person for 2 different points of view in this book. It was appropriate because both characters are important to the story and they have very different worldviews. The style of narration is (and I use Mark's words to me) "1st person smartass."
Stone understands plot. This story gets quickly into conflict and the pace steadily builds, with setbacks and surprises along the way. The book has the feel of a James Bond movie, with violence mixed with wry wit. This might bother some: there is lots of violence, and it is often graphic. I did not find the violence gratuitous though. Considering the adversaries, the amounts and kinds of violence seemed apt.
Magic is used in the story, and I liked Stone's magical theory. He makes use of botanical magic (potions and balms), Elemental magic, and magical Words of power. In his model, the vocabulary of magic Words are distorted fragments of the original divine words of creation.
If you like action, wry wit, mythology, theology, and aren't put off by copious violence, you may very well enjoy this tale. I did. I downrated it to only 4 stars because I found a good number of tiny editing errors that should have been found when proofing, and there were enough of them to be bothersome.