I grabbed this book to read a chapter of before I went to sleep tonight. The same thing happened with Will Grayson, Will Grayson -- something about John Green's books resist the effort to stop reading. This book is so saturated with depths and resonances, I can't imagine how a person could read it and not feel deeply moved and changed, or at least reinforced in their most worthwhile convictions.
I also feel it's very important to point out how much I absolutely adore the methods by which John Green grants himself license in this book to write like he's writing the Great American Novel, and still keep the tongue-in-cheek tone of playfulness that surrounds those speeches of depth and resonance, managing to avoid letting either undermine or overpower the other. Characters at a few points call it pretentious, but I don't think that's what it is. The Fault in Our Stars, especially with regard to Augustus Waters, takes real, unashamed and unselfconscious joy in noticing the world and human life, and in using language and behavior to share that experience in a beautiful way.
I found this book deeply moving, and I can't wait to read more of John Green's work.