Things I liked:
The overall story held together pretty well, I didn't notice any big discrepancies or contradictions. The idea of people changing forms into either real or mythical animals was an interesting one, and handled pretty well. The fantasy world was well-imagined. Ivy was a good protagonist, fairly sympathetic but also not so perfect as to be unbelievable. A lot happens, there are a few twists and turns, and overall the story kept my interest.
Things I didn't like:
The book could have used a more thorough editing and proofreading. There were some things that could have been better explained, such as the places the students went to in the tents—were they real places, places in their minds? That might better explain why Ivy succeeded at firing a bow on her first attempt at it in one of those worlds, while struggling to learn to do so in real life. The God talk was handled clumsily, we get little hint of anything religious in Ivy's life yet she ends up praying to some Lord at a couple of points late in the book.
I pretty well enjoyed this book. There are lots of good things here, but a few problems, too. Perhaps some things will be explained in later books of the series. I wait expectantly for the next book.