The first thing that comes to mind when I reflect upon this book is: ambitious. 
 This book (and from how things are shaping up--the entire series) is incredibly ambitious. This is Brown's debut novel as well, which sort of adds to my awe of the whole thing. 
 Though things sort of start off in the predictable "society is keeping secrets from you to keep you under control" vein, Brown brings his own twists on the trope and the result is a rollercoaster of a tale. 
 The set up of the society isn't particularly unique--ruling class superiority and then others divided by profession through to the bottom of the caste system. But this book is only marginally about that side of things. And I will say that I'm looking forward to seeing it get fleshed out in future instalments. 
 Darrow, on the surface, seems to be an unremarkable character. But as he undergoes change throughout the course of the book--well, I wouldn't exactly say that I ever fully identified with him. But I understood him. And I sure as hell was rooting for him. 
 I've seen this book classified as YA--which I understand given the ages of the characters. But I mostly disagree with that classification. Brown does not pull his punches here and the story does not hold anything back. Darrow gets thrown into a war (albeit, not a "real" one as it's pitched as "on-the-job training" for the school) and war is a brutal, savage thing. 
 Brown also does an exceptional job of keeping the stakes high. No one is safe, not truly, and there were a number of surprising character deaths. There was at least one character that made me think, "Did they really have to die?" And then I realized the answer was, "Yes." Not just because of the consequences for the story (and character relationships) but because really, why should I have expected them to be safe and exempt from death? Just because they were a named character who I had time to get a bit attached to... it made their death that much harder. 
 The whole book felt like that. Rough. Brown puts his characters through hell and back. And it's remarkable to see how they respond. 
 Now, a good portion of this book relies on military style strategics. There is a lot of time devoted to this. Keeping track of all the players, weighing the options, battles and retreats. So if that isn't your style, you might have a hard time with this book. 
 That said, it's all written in such a way that is very comprehensible. While Brown doesn't skimp on the details, he also doesn't bog you down in unnecessary technical minutiae. And the strategies his characters use are fascinatingly desperate at times. 
 Overall, this book far exceeded my expectations and I enjoyed it a hell of a lot more than I thought I was going to. I cannot wait for the sequel in January!