Fantastic. 
It's hard to put into words, but something about the way this story is written is what helps make it metal. If I were reading it as a book I might've lost interest, but hearing it spoken helps make it better. I actually don't mind the sort of simplistic straightforward prose: it matches Hekat's beginnings and stalwart devotion to the God, as well as the general Barbarian tone to the world. Haven't read anything else by Miller, but it just fits 
Pacing-wise, it is slow. Then A LOT happens in the last fifth of the book, with lots of time skips. 
I love the way she worldbuilds without TELLING you. Like, she never explains Godbraids or highnoon, but by the characters thoughts and treatment of these ideas, you get what they are and why they're important. It really does a great job immersing you in the world and how cruel it is. 
Also... I think I just love the setup. I love the take that there IS a God, not just a religion or flying solely by belief, there is an actual, quantifiable God. A God who DOES grant power and DOES smite via the tools who speak for him. After a time, you KNOW Hekat is a powerful tool for the God, and she has unwavering devotion in him. The struggles in the book are not so much Hekat's as they are THE PEOPLE AROUND HER trying to stop her and preserve their way of life. But as you read, you can see the rising tide and how inevitable their struggles are against her. Yes, she's a bitch and brutal, but she is also literally doing as her God commands. And no one can stop him. 

I highly recommend this!