This book is as fitting an end to the series as the third one was. Scalzi does a good job of wrapping things up so that if this book truly was the end of all things Old Man’s War, you’d be pretty satisfied. I don’t know if he knew whether his $10 million deal with Tor would pan out or what it would contain specifically, but we know now he’s contracted for one or two (I can’t remember the exact number) more books in this series. Still, if he died tomorrow and/or never wrote another book in the series, this would be a good end.
Basically, it’s a continuation of the last book and the end of the second era of the Old Man’s War series. Era 1 being the Colonial Union vs Everyone Else (Books 1 and 2), Era 2 being the startup of the Conclave (Books 3 and 4), and Era 3 being the aftermath of the end of Book 3 (which I’ll kindly not spoil). This new era has a new equilibrium and a new sandbox for Scalzi to play in. Whether he goes in that direction or does prequels or, like Zoe’s Tale, a side-quel – I don’t know.
In structure, this book is just like the one that preceeded it, (The Human Division, in that each chapter is somewhat self-contained. It’s also split into parts that each have a different POV character. Plot-wise it clarifies and expands upon plot from the previous book. Unfortunately, there is a lot less Schmidt and Wilson.
Finally, it was interesting to read this book now with the troubles with ISIS so prominent in the news. The enemy is essentially a terrorist organization and part of what this book deals with is how hard it can be to get one’s hands around that. If you consider the reality that there are nation-states that sponsor terrorism to meet their short term goals, it really completes the parallels.