I really don't know what to make of this book. There is a world there with different species of human, different tech and customs and yet it feels overdeveloped. The different scents that mark each species is an interesting one, yet I couldn't get a feel of who these people were or what the world was like. I also couldn't understand what the 'core' thing was all about and why they wanted her. Despite some 'listen to your heart' words of wisdom, it didn't seem to actually do anything.
The characters were interesting but unfortunately I couldn't understand why the baddies wanted to capture Kayli-el, why the boys helped her and why her teacher was killed. Part of the problem is an editing issue, the writing is good but there isn't enough build-up, or lead in to the story.
Despite the above however, I didn't hate it. The characters held my interest through some of the more confusing parts of the story, but I don't think I'll read it again.