This was a rather disappointing read. The synopsis on the inner flap of the book suggested a gripping adventure; instead the authors chose to focus on developing the relationships between the characters. I don't mind character-driven books, when the characters are interesting. Unfortunately, out of the four main characters, only Rook really stood out. Thom grew on me a little, by way of his interactions with Rook. They had a really interesting dynamic and lots of sexual tension between them; they, along with the Dragon Corps, were my favourite part of the book. For a while I thought they would end up together but the authors pulled a really weird plot-twist out of nowhere and made them long-lost brothers instead.
Meanwhile, Royston and Hal had no real chemistry and yet the authors spent so long detailing their nauseatingly sweet, and ultimately tedious, romance. It also didn't help that the character of Royston seemed only to be there to provide exposition. I basically skimmed most of their parts so I could get to Rook and Thom. There were some interesting minor characters that I thought the authors could have dedicated more time to rather than to the boring Royston/Hal scenes, like the other members of the Dragon Corps who had some very funny scenes and proved that at least the authors could write some witty banter.
The plot itself, the bit in the synopsis about four different men coming together to save their country in one final battle, doesn't really come in until the last 80 pages or so. And when it did happen, it didn't have any real sense of urgency. The book takes place in a setting where two great empires are at war, yet there was never a sense of real danger in the book so the climax (the final and only real battle scene) fell a little flat.
Also, some things were just really farfetched, like a university student being sent to teach what is basically manners to a group of elite soldiers or Hal's ridiculously simple and obvious solution to the magicians' crisis. I got the impression that the authors had a lot of ideas for this book (giant metal dragons! young student vs. dangerous soldiers! gay magicians! war and intrigue!) but didn't know how to put them all together in a way that made sense. The result is a very uneven book that has a lot of wasted potential.