A story about kids with cancer + countless reviews mentioning bawling their eyes out = someone is going to die. Needless to say, I proceeded with this assumption and considered myself immune to feels. 
 ...I have to admit my eyes did indeed water. A little. That is pretty telling, for I'm a soulless human being, you see. So this is a big deal. 
 That being said, this made me laugh WAY more than expected. Great humor and there were lots of really deep and thought provoking moments. The characters were a bit "old and wise" for their age, but I don't mind because honestly? It made it a better book. I'll just pretend that having a terminal illness makes you mature faster and turns you into a philosopher or whatever. 
 All in all I can see why this is so vastly popular.