I liked this book just fine, which is kind of disappointing since I thought I'd love it... The premise is very interesting, and raises a lot of questions (all of them falling somewhere in the area of “how does it work?”) that are fun to think about but don't necessarily require answers (for me anyway), but in the end the execution fell flat for me. I could not get into the characters at all and I kinda wish the story had been very different with a different set of characters. A lot of the writing felt to me like it belongs on the “I'm 14 and this is deep” sub-reddit, it was trying too hard to be poignant and profound and sad but it just dragged on and on and it was frustrating to read.
Another review mentioned the overload of sadness on every page kinda ruining it and I couldn't agree more. It's like every single character had something tragic going on, I couldn't bring myself to care, and it just lessened the impact of the central element of these two teenagers being doomed to die. Throughout the book the main characters don't just run into a bunch of people, we also follow some of them in third person narration and it takes up a good chunk of the book and it added nothing at all for me. It felt utterly pointless.
At least it was a quick, easy read, and it wasn't bad, but this book didn't do it for me at all.