I read the first chapter, instantly got invested in the characters and their friendships and knew I'd love this book. I purposefully started reading this after Sunrise on the Reaping, because I thought "well, this book can't destroy me more than that". Turns out I made a good decision, because while I was correct, this story also hurt a lot. The "hopeful"-tag is a little debatable, I guess.

This book is beautifully written. Very rarely the author could've toned it down a bit for my tastes, but for the most part I loved it. I struggled a bit with the concept of the story and enjoyed the current timeline more than the one taking place in the past. I understand why it was necessary though.

As said, I think the characters were what I loved the most, they were instantly wonderful and the friendships and romantic entanglements felt very real and as intense as teenage emotions are. 
As far as I can tell without having any similar experiences, this book also felt very authentic. This is written in a way that actually feels like someone who knows what they're talking about wrote it - which is the case. I watched a YouTube video by the author, who said something like "I wanted to write a story about kids like us, because most of the existing ones are written by people who aren't chronically/terminally ill". 

Little side fact: If you're German and watched "Club der roten Bänder" and liked it, this felt similar in some ways.