Wow. SO readable. I really liked this (yeah, I know I know, why I'm not giving it a four? Well, I only have given ***** to books I want to reread every five minutes and possibly copy out by hand so I tend to save my **** for books that are not simply readable but extremely excellent.) 'rock' is a good young adult book, mature, well structured, tense and nailbittingly romantic but it's not quite a masterpiece. If you want some family centered m/m lonnnnnng teen/young adult romance you are in for a treat with this sweet but never fluffy, but it isn't the place to explore the meaning of life, too (and that's cool!) 
 One thing that felt kind of strange to me was Cooper's anxious behaviour, it recurred through the book and it obviously had an explanation (Cooper starts to give it when he meets Jace) that goes beyond 'a few quirks' but it's never explored further than that. I could live and in fact, I could support not naming names and foregoing labels but I found it odd that the issue was set up so neatly and then kinda left by the wayside even in times of great anxiety and stress. Cooper clings to his stones, and that seems to fix it all... I'm not sure if the author was trying to portray disability of some kind, the spectrum of abilities/neurological differences that comprise all of humanity or what but that part of Cooper felt somewhat incomplete.