Tldr: 3/5 - I did like how the stories ended, but I don't desire to reread/keep the book. And I really liked the 1st short (4/5)

I don't know how to rate this book because my enjoyment level was a rollercoaster throughout.
Maureen's was probably my favourite; Green's and Myracle's tie up in the end. Many people say that Myracle's protagonist is a very hard read, but it wasn't much different from John's, in my opinion.
That was the reason for the rollercoaster. It's very hard to get to the point where you enjoy these characters, and in some stories you don't really. I suppose it's a "care about their journey" book.
Lastly, you can definitely tell the book was written in 2008 - there's a weird hate of cheerleaders, for example, that is in some ways justified, but the way it was handled in All Three Stories made me uncomfortable (although I only know cheerleaders from american movies)