I really enjoyed this book. 
 I loved the plot, I loved the characters, and I loved the world. 
 The trolls and their magic system are indeed fascinating, it was really well written and developped. I loved the whole politic aspect of this book. It always adds something more. 
 Cecile is a great protagonist. I loved seeing her grow, I loved seeing her become stronger and better. The romance was well written as well. There was no insta love (thanks god) which I really appreciate. Tristan is also a gret character, he isn't the typical moody guy (I was afraid he might be just that at the beginning but no) 
 However I thought it was dragging a bit in the middle, I find myself almost bored at one point, that's why it is a 4 stars book for me. But the end totally made up for it. Overall it was a really good book that made me want to read more.