Not quite what I expected from the cover. In my experience of oil-paintings-of-planets-and-spacecraft covers, you tend to get pretty hard SF to go with them. This was more extra-firm tofu hard. The cover blurbs compared him to Heinlein, which was fair.

The book has a couple of reveals, the first of which I genuinely did not see coming, and the second of which I saw coming for a while, so I'll separate my review into the bits I can talk about without spoiling and the spoilery bits.

John Perry, the protagonist, is seventy-five when he joins the Colonial Defence Forces. Those recruited by the CDF never return to Earth, and are never heard from again. No one knows why the CF recruits senior citizens, and in fact, doesn't permit you to join younger than seventy-five, but the assumption is that they must have some kind of rejuvenation technology, because a seventy-five year-old isn't otherwise the ideal soldier.

Although many things in this book are Heinlein-esque, Perry is much older than the average Heinlein protagonist, and noticeably wiser, (although perhaps not as smart) which was a bit of a relief. It's nice not to have to watch a protagonist make mistakes the reader can see coming. Yet, Perry is still enough of a risk-taker to step out into the unknown.

SPOILERS FOLLOW

This book has two different kinds of fridge problems. The first is what TV-Tropes calls fridge logic: those logical inconsistencies which don't particularly bother you until you're finished the book, and, in a moment of boredom, suddenly realize part of it makes no sense.

It turns out that the CDF's plan for the elderly that it recruits is this: ten years before they reach the age necessary to join, they're signed, and given a rudimentary physical. Using materials culled from this physical, individual clone-bodies are prepared for them, and given significant upgrades. If, ten years later, these people still want to join (and are still alive), their consciousness is uploaded into their clone-bodies, and they become soldiers in war against any and every alien species that challenges or threatens the colonies.

However, given the population they work with, some of the people who originally were recruited don't make it to seventy-five. In these cases, the bodies prepared for them are given a basic personality template, soaked in military learning, and become "ghost forces," an elite company which have never known anything but war, and who are so well adapted to their specialized soldier-bodies that they use them more efficiently than anyone else ever could.

In the case of the book, the Ghost Forces exist so that Perry can encounter a body grown from the DNA of his dead wife, Kathy. It was actually done much better than I expected-- as I said before, Perry is old enough not to be stupid. He doesn't harass Jane, the woman living in Kathy's body, or expect her to be Kathy, although he is fascinated by her. He quickly grasps that she's her own person, and treats her that way.

However, the fridge-logic is this: if bodies without a personality upload are more effective soldiers, why bother with the personality upload? In fact, why bother with the DNA collection? Surely one could make a thousand, or a million soldiers with the same DNA, just as efficiently, if not more so? Why train soldiers who already have bad habits from a lifetime of living, and who have adapted themselves to Earth, when you can start fresh with someone who will only ever know war in space? I think the answer is "it would be a different story."

The other fridge problem is who goes in it: The soldiers are told when they go through basic, that the odds are against their survival, and indeed, most of the people Perry trains with die, including the explicitly homosexual Alan. Scalzi sort of seems to write about straight, white men, although there are generally enough others thrown in for representation's sake.

It's mentioned that those from the Indian subcontinent are permitted to join the CDF earlier than seventy-five, presumably because their life expectancy is shorter. However, the only time that continent comes up is when a racist ass pontificates for the sole purpose of allowing Perry and another (white) recruit to bond over slapping him down. After they're popped into their new bodies, they're told racial divides have been abolished since there is no longer any skin colour but green. (The new bodies are chlorophyll enhanced, among other changes.) I am somewhat sceptical of this. One of Scalzi's commanding officers is mentioned to be from South America: she dies.

The Ghost Forces are named by a simple convention: a common first name, and the last name of significant philosopher or scientist. However, they seem to be given common English first names. I didn't notice any of them named Samir, or Jamila. The only non-English last names I noted were those of ancient Greeks. (I admit, I think a soldier named Gandhi would be hilarious, but probably somewhat offencive, so, perhaps just as well.)

(Although I should note that the person who makes this claim identifies himself as Latino, and doesn't, so far as I can recall, die.)