Matthew Quick does an excellent job of creating characters who are mentally ill or stunted or otherwise just a little bit off and making them relateable and likeable and sympathetic. All of the main characters struggled mentally in different ways. While this book felt less meaty and heavy than Silver Linings Playbook, it was still a very enjoyable read. 
 As a sidenote, I really enjoy Quick's treatment of Catholicism in his novels. He has religious characters, but he doesn't belabor the point. Their religion is a part of their lives, but his whole novel isn't centered around it. And his priests are certainly not saints, but they're not evil either - they're just human.