Mostly, I loved this book. The world-building was great, and it was really interesting to read about all the aspects of mage life. I also loved the character of Titus, with his busy brain always thinking of the next step. 
 This would have been an easy 5 stars if it weren't for one thing: Iolanthe's character flaws. Or rather, her lack of them. She is so good at EVERYTHING (magic, cricket, sarcasm, pretending to be a boy even though she looks very girlish, etc etc), and she doesn't even have any personality defects to make up for it (and being wary of Titus does NOT count as a character flaw!). Major Mary Sue vibes here. 
 Time to see what the next book in the trilogy brings...