Paizo doesn't cut corners or make a hash out of selling their campaign setting; this is particularly true with any major new contributions they bring to the setting - such as the continent of Tian Xia. Master of Devils complements the Jade Regent adventure path, along with the campaign setting and primer for the Dragon Empires.
The novel features Count Jegarre, his hellspawn bodyguard Radovan, as well as a slightly unlikely third companion, the hound Arnisant. Jegarre and Radovan's adventures have graced Pathfinder fiction in various forms previously - most notably in the novel Prince of Wolves. As such, avid followers of Paizo stories can enjoy the new exploits and developments in the characters, which lends the novel a certain degree of authenticity. The characters do not merely exist as cardboard cut-outs for the story, but have the luxury of depth and extended development.
The story itself takes place in Quain, a nation of heroes in the continent of Tian Xia - the Dragon Empires. The word "hero" needs to be taken with a pinch of salt (as the novel points out on more than one occasion) and is more intended to mean "warrior of great renown or infamy" - well suited to a nation of warrior monks. As such it should not come as a great surprise that a particularly powerful hero, who calls himself Burning Cloud Devil, creates the main impetus in the story. He uses the quivering palm strike to literally hold the life of Radovan in his hands and uses this to pressure the hellspawned to comply to his demands. At the same time Jegarre and the dog Arnisant each have their own story to follow with many characters and intrigues to fill the pages. All three characters ultimately serve their respective comrades in a way that draws everybody together for the climax of the novel.
The author chooses to tell the story from the first-person narrative; which can be slightly jarring to the reader when he switches between characters. Each chapter is dedicated to a particular character, either Jegarre, Radovan or Arnisant, and consequently narrates in the "I" perspective. Once this becomes apparent to the reader, the flow of the story becomes swift and quite enjoyable - as Dave Gross manages to believably inter-mingle the events between the three main protagonists in such a way that thoughts started by one character get completed by another in a different chapter. Seeing the metaphorical footprints of the various characters in the other characters' storylines creates an enjoyable recognition and makes for an exciting and believable story.
Another feature that draws comment and praise is the change in prose that the author introduces for each protagonist. The first-person narration is intimate and lends itself to a much deeper insight into the psyche of the characters that are portrayed when compared to other styles of narration. In this case the arrogance of Jegarre, the flippant nature of Radovan, and the simple canine thoughts of Arnisant each uniquely color and flavor the chapters in which the respective characters lead - but at the same time make it vividly clear that each of the characters is complete and complex individual. What makes this a particularly appealing proposition is that of introduction: all three of the characters are foreigners in the strange lands of the Dragon Empires. That means each of the three gets introduced and digests a different perspective of the quasi-Asian setting that Paizo has developed, and in the process the reader is naturally given access to these lands as well.
The story is strong and fast-paced, in spite of taking the time to flesh out the flavors and thoughts of a strange continent. I would have thoroughly enjoyed even more of Dave Gross' palette as he brings the world of Tian Xia to life without ever needing to tell the reader "hey, pay attention now, this is what the world is like". His rendition of the capricious Monkey King, his treatment of the disparate and sometimes truly bizarre nature of the kami (a form of spirit), and the sometimes unexpected wisdom of warrior ascetics, to name but a handful, truly colors a rich tapestry - and the subtle nature by which the author does this is worth emphasizing: the story flows naturally, in pleasant swirls and eddies and yet still carried along swiftly to its ultimate conclusion.
I've only had the pleasure of two books in the Pathfinder Tales range - the other being Death's Heretic. Perhaps I am biased, for my love of Eastern stories, but although both are very enjoyable stories, I favor "Master of Devils": the plot and characters are more complex and the various threads are interwoven more richly to produce a thoroughly satisfying story that I do not hesitate to recommend.