So I really enjoyed book 1 and this book as well. The only issue I had was the emphasis on Zack. There were definitely some interesting parts of his story but I think the book would have been better if the focus was mainly on Ryun (who is the more interesting character in my opinion) with a few more interludes that catches the reader up on what Zack has been up to.
Other than that the book was great. I really like the Past fragments. They give the characters more depth and it gives some context for the beginning battle of book 1. If Zack and Ryun end up fighting at some point I will be cheering for Ryun.