My first reaction when I finished this book: Imagine Brent Weeks had channeled Brandon Sanderson and you're halfway to knowing what kind of book this is going to be. McClellan has developed a magic system that is very reminiscent of allomancy - powder mages snort or consume gunpowder much like a cocaine addict, endowing them with powers physical and metaphysical. We also see magic in the more traditional sense (hand waving wizardry so to speak), Knacks (people with one off powers, X-menish but without the flair), all resting in a world we can almost recognize as being modeled after late 18th/early 19th century Europe. And like so many books I've stumbled into recently, a B plot centered around religion and gods. 
 The initial hook for this book is the calling in of a retired investigator to solve a riddle left by a dead sorcerer at the end of the coup that brought down the King, spiraling out from there to include rogue magi, betrayal among the coup's conspirators, and a civil war. Good stuff, to say the least, and where McClellan might be faulted for a lack of depth, he more than makes up for by keeping the novel at a brisk and relentless pace that hurtles the reader to the conclusion of the first volume far too quickly. A little cliche, but a lot of fun to read, and yet another author/series to add to the queue.