Every time I start reading a book in this series I'm sceptical. Its all very-on-the-nose, very staged, contrived. But before I know it I'm 75% through it and curious to find out how it ends. There is something comforting about the structure and message. 

Deals with some pretty dark scenarios but ultimately the message that comes through is both clear and surprisingly sophisticated. Dealing with grief / trauma isn't about undoing it or fixing the past. There are no miracles. But there can still be healing in facing the past, looking at it through a different lens and then letting it go so you can move on. 

I liked this a little less than the previous ones. The emphasis on more people travelling to the future gave the writer scope for new scenarios but I felt increased the level of contrivance a little too much. I preferred when it was kept simpler. The concept is already balancing on a knife edge in terms of becoming ridiculous - this teeters a bit closer to the edge. 

The writing style isn't exactly elegant. Explanations are heavy-handed and not much is left to the readers to decipher.

Also be conscious this talks about suicide / terminal illness in a very blunt, matter of fact way that seems odd to western sentiments. If that's an issue for you, approach with caution