My reading of this book is probably due to a series of coincidences. Another book from Scalzi, Redshirts, has been on my radar for a few weeks/months - so I knew the name. And then, the EBook Humble Bundle appeared, and I bought it, and there was this book in it. And that day, I thought that I had forgotten my (dead tree) book (I hadn't, it just wasn't in the bag in which I thought it was), so I browsed my Kindle app content, found that, told myself "oh well" (I was not convinced by the title), and was hooked within a paragraph or so. Or possibly within the first three sentences: " I did two things on my seventy-fifth birthday. I visited my wife’s grave. Then I joined the army."

The whole book is very similar to Starship Troopers, by Heinlein - Earth is reasonably healthy, but war is everywhere in the galaxy, and aliens are not the most peaceful creatures ever. And to fight a war, well you need soldiers. In Starship Troopers, soldiers are mostly young adults/kids, and military service is a way to attain "citizenship" (the right to vote, essentially). The premise of Old Man's War is pretty different: people enrol at their 75th birthday, in the hope of accessing a better health - even if noone knows what happens in reality (because it's all managed by the Colonial Defense Force, whose interactions with Earth are minimal), the general consensus is that you cannot wage a war with 75 years old people, so probably they must do something for that. In the book, we follow the narrator, John Perry, during his enrolment and subsequent career. And it's a very, very enjoyable read. Again, the reference to Starship Troopers are obvious - but it's a "revamped" version of Starship Troopers - and much more funny (there are some great dialogs in there - I laughed out a few times in the train yesterday - sorry for that, neighbors).

Really a great book; I was kind of afraid of Redshirts because I really loved the premise but I was afraid that the book would not live to my expectations; now I think it will, so I'm happy :) Also, Old Man's War is actually the first of a series of (to this day) 4 books; I think I'll read the rest.