I’d heard from a number of quarters that this was good, and hey look, everyone was right! Set in a future where Earth has managed to colonize some other star systems, the colonial defense forces recruit 75-year-old folks from Earth with the promise to return them to fighting shape so they can put in ten years of service in the war against the nasty human-eating aliens. If they manage to survive their ten years they can become colonists themselves and have a whole new life.
I’m not usually a huge fan of military SF, but Scalzi’s army populated with people who have lived a whole life already allows him to sidestep most of the obnoxious cliches that result from putting kids with no experience into military situations. Not that there aren’t any blowhard jerks, but the few who make it through basic training find their arrogance resulting in unfortunate mishaps on the battlefield that are disturbingly enjoyable to read.
Lest you think the book is all guns and gadgets (there are plenty of those. I want a BrainPal.), it’s also got some sex and romance. The romance is mostly in the main character’s love for his dead wife, but it is no less touching for its confinement to the past tense. The other romance would be a big fat spoiler (also a mind-boggling coincidence, but I let it pass).
Great fun, and there’s a sequel (plus a short and a novella if I’m interpreting the internets correctly).