Really, really good worldbuilding. I definitely recommend reading the novella that comes with this book that details the onset of Hayden, because it was so interesting to see the world adapt.
This book mixes illness, technology, disability, and politics so well. As with previous Scalzi books, I have read, the "realness" of the worldbuilding was definitely the greatest achievement of this book. I mean, wow, I picture myself living the lives of all of these characters, and living in their changed world. Which isn't a pleasant thought.
Scalzi explores all the implications of his worlds, all the nuances, and no one gets left out. He explores how issues affect those high up in society, those downtrodden, those incarcerated, those just born to those who are old. I love Scalzi's sci-fis, yo.
I listened to the version of the audiobook narrated by a female narrator. For the sequel, I will probably switch to the male one, so see what that's like. It's cool that you can do this XD. You don't often read epic stories being completely gender neutral.
The plot was fun, always in a mood for a good cop murder mystery. The worldbuilding ties well into the mystery, because how can you find a murderer who hid in the bodies of others?
More sci-fi than thriller!