Holy smokes this book is sad. Really, really sad. I knew it was about kids with cancer so I was expecting it but it still blew me away. The story is beautifully written, the language used is impressive and wonderful. The characters are all very real and I felt deeply for them.
This was my first John Green book and, prior to this book, I had no other experience with "cancer kids" in literature. I expected the story to be really sad but...it really wasn't. I generally appreciate snarkiness and Veronica Mars-like intelligence and quick wit in teenagers and I got a lot of that dialogue so that was welcome. I guess what was missing for me was a deeper connection to the characters. Maybe all that snarkiness kept me at arm's length and, although I was moved at some level by the struggles each kid faced, I wasn't emotionally invested so...no tears for me.
I've both read the book and watched the movie. I love it. Some of the dialogs are a bit too witty/profound for me to believe they're from a pair of 16-17 years old (in the same way you'll find many dialogs in movies unreal). But I understand they're that way for a reason: so that the writer can provide his views (via the characters) and so that it can amuse us and hold our attention. (Believe me, if you write exactly like how two cancer kids talk, your readers will slam your book to death instead of praising you "oh it sounds so real").
Now back to my love for this book. I don't find it excessively (holy-smokily) depressing, nor is it necessarily a tear-inducing novel (either because I'm a guy, or because I'm weaned on much more bleak/sentimental writing from the world of non-English-speaking literature). It's indeed sad though, and real, and funny, and heart-tugging, and melancholic, and it gives you that moment to sit back and think about your life, your own mortality and what it means to exist on this earth at all. That part, the part of the existential questions and opinions, is what I like most about the book, although the average readers don't seem to give it any thought at all. I know the opinions (either purportedly from Gus, from Hazel or from that fictional Van Houten character) are all from the author (although he may just restate belief he first got off someone else), but that doesn't mean they're not intriguing or interesting or profound. Do you really exist to leave your "scar" to the world? To live an imprint to the ones you love? Is there a Something after you're gone? If you're among the 99% of people who leave no "scar" worth mentioning, does that mean you've lived in vain?
I guess I'm veering off into a direction hardly anyone else wants to go in, but if you ever have an inkling for that sort of thoughts, read it and feel it and think it for yourself. Or maybe just read and enjoy a really good piece of literature.