Disclaimer: This is only the second John Green book I've ever read (Looking for Alaska was my first). I had no idea about the hype surrounding this book nor was I even aware of the rather large and enthusiastic fanbase that surrounds and follows John Green. 
 I think the fact that I came into this book without knowing anything about the cult of John Green made it so that the common complaints about this book didn't affect me at all. Since you've probably read all the gushing reviews about this book, I'll lay out the common complaints about it and why they didn't bother me. 
 Complaint #1: Apparently the book follows the same old "John Green" formula. 
 Since I am relatively unaware of this formula, it seemed good enough to me. 
 Complaint #2: The 16 year olds don't speak, talk, think like your average 16 year olds. 
 Ignoring the fact that these aren't your average 16 year olds anyway since they've spent their most formative years thinking about their mortality, I am still ok that this is true. Why? Because when I read books where the 16 year old protagonist sounds, looks, talks, thinks and reacts like your average 16 year old, I spend about half the book focused on quashing my feelings of extreme irritation at that character. I like reading about 16 year olds who aren't your average kid, which is why I spend most of my time in crazy, dystopian scenarios. If I wanted to read something that sounded genuinely sixteen, I would just pull up my livejournal entries from 2003. 
 Complaint #3: It's a standard 'cancer' book. 
 I'm not really in the practice of reading 'cancer' books. In fact, I didn't even realize this was a genre so I can't really speak to whether it does something different with the subject matter or not. I do think that it depicted illness without glamorizing it. I think that it spoke about pain and grief without being in love with the idea of suffering. People who were looking for a more 'realistic' look at illness, apparently meaning one in which the characters spend the entire narrative consumed with their pain and suffering before finally succumbing to their death in a blaze of bitterness and anger, were always going to be disappointed with this book. And if that's what you're looking for, totally cool, but I'd strongly advise against reading it. But for me, I find nothing contrived or misleading about finding a bit of hope in a rather hopeless situation. I'm glad that Green focused on the living of life rather than the ending of it. I don't hold it against Keats for choosing to write poetry rather than angry letters about death, and I don't hold it against John Green for focusing on the little bits of happiness one can find in their lives rather than the bitterness of losing it.