First off, I enjoyed this novel. It has a good story and interesting characters, and the author doesn't make it too easy on them. The characters are relatable, multi-dimensional, and flawed, they have clear motivations for their actions, and their actions are consistent with those motivations. It's the third novel in a series I haven't read the first two novels in, but it is reasonably self-contained and reasonably kind to the reader who is joining the story in the middle. The use of common fantasy tropes makes the world comprehensible, but the author seldom leans too hard on them to do the important work of world-building and storytelling. At the same time, he makes them his own, both by redefining certain characteristics of common DnD/fantasy races and by injecting Aztec mythology and symbology into the mix. It's a cool world, and it's self-consistent, which makes it better than a great deal of those in fantasy novels by little-known authors. The magical and dubiously useful map to the entrance of the Labyrinth was particularly well-handled.
On the other side of the coin, the prose is repetitive, often giving important information several times. It's not uncommon to have a new piece of information introduced appropriately in a chapter and then repeated, as though in clumsy exposition, in the next chapter; most commonly this appears as presenting the characters' motivations by way of explaining why they're making decisions for which the motivations were perfectly clear. There's at least one instance of a character's privately and internally making an important discovery about another character's background, which is immediately a topic of conversation between all the characters as though it were an object of general knowledge. Important powers and items seem to magically appear when they're most useful—Rev's father's sword (to my memory, at least) was first mentioned when a magical sword was necessary and then was used over and over again to get our heroes out of scrapes for which it was the only possible solution. Rev's use of Shi went from something tenuous and difficult to something he had completely mastered (because he used it, with great effort, to clear some brush...I think?), and he consistently developed new powers and masteries along the journey (supernatural fighting, sneaking, and character-judgment skills) as needed, which were then explained away as the result of training in his youth—granted, I could be overstating this, having not read the earlier books, but it often feels pretty convenient. My biggest complaint, though, and I know I'm complaining a bit here, is the author's use of figurative language. There are frequent similes that are often cliche, imprecise, and occasionally inappropriately anachronistic, which pulled me right out of the story, sometimes several times on a single page. My only real gripe about the story itself is that despite having a team of very capable companions, by the end, Rev has become the only useful character and the others are either people he has to protect or direct obstacles to his success.
Overall, this book was enjoyable, but wasn't for me. Honestly, I am not your standard casual reader of fantasy fiction. I read slowly (both by preference and bad habit), and this is a fast-paced book that I imagine is meant to be breezed through without my particular brand of overthinking. If you can do that, you'll likely love it. It certainly has a lot going for it.