I should mention up front, by way of full disclosure, that scalzi and I were co-conspirators on the Chicago Maroon and the Breakdown comic book project back in our U. of C. days. Whether that means I'm more likely to logroll his novel, or minimize it just to imagine his squirm, I leave to your judgement. As an additional data point, however, let me note that he was man enough to give me the Maroon's hardcover review copy of Eco's Foucault's Pendulum because I clearly deserved it more than he did. I forget if he ever wrote a review of it.
So anyhow, my old college chum wound up writing Old Man's War, a John-Campbell-Award-winning novel that has been pretty universally compared to Heinlein, and not to the overly logorrheiac later Heinlein, either. In San Ramon, I cashed in a Borders gift card from Christmas and picked it up in mass-market paperback, and cranked it pretty much straight through. So, readable? Very. The comparisons to R.A.H. come not merely because of the relatively clean prose style or even the subject matter -- a man joins the space infantry, discovers a bigger world -- but let's start there. The battles are exciting, but cleaner than Heinlein's battles, and lack the immediacy of, say, David Drake or even Jerry Pournelle. Scalzi's John Perry, meanwhile, is less colorful than, say, Honor Harrington or Alois Hammer. This is neither A-1 SFnal war writing nor A-1 carnography, in other words, although it's less slick (and hence much better) than John Ringo or S.M. Stirling or their ilk.
More interesting is the Heinlein-like brusque exposure-adjustment-expansion structure ("man encounters strange thing; man deals with strange thing; man encounters stranger thing; repeat until novel ends"), and the occasional swing through Heinleinesque didacticism. (To be fair, a habit hardly restricted to Heinlein or Scalzi.) We meet, for example, a former Senator who believes in peace and negotiation, and who dies an improving death because of his naïvete. We learn that fat bigots die, and good riddance. Etc., and it's on to the next chapter and the next strange thing. The universe comes to resemble more David Brin's Uplift cosmos, although not quite turned up so high. And on our hero goes.
Part of this works because unlike the eerily mature and articulate young narrators of many Heinlein novels, our protagonist is 75 years old. He's come by his cynicism and world-weariness honestly, and he volunteers for the Colonial Defense Force, which only wants old soldiers, considering young ones too unskilled and too much trouble. (Except when they don't. I don't want to spoiler anything, and maybe it's dealt with in the sequels, which I haven't read, but ... well, Scalzi elides the premise in a pretty major way later in the novel. Not unskillfully.) Perry goes off Earth, and learns that ... well, we covered that part -- the universe is big, strange, and deadly. There's a minimum of classroom lectures (although a good Heinlein lecture is usually a better read than most people's whole novels) and, as I mentioned before, a cracking plot through which our hero hurtles with aplomb. Perhaps too much aplomb -- even 75-year-olds might not take interstellar warfare in stride, and nobody seems to wash out of the CDF much on psych grounds -- and perhaps too much plot.
One of the things you don't notice at first about Starship Troopers (which, if you're just joining us, is the clear and present model for Old Man's War) is the very ordinariness of Juan Rico. Sure, he survives, and makes officer, but he's not the Audie Murphy of the Bug War, or even the Richard Sharpe. He's just an average, spoiled civilian who becomes a skilled, but not exceptional, Everysoldier. By contrast, John Perry is something special, and -- again, no spoilers -- the laws of chance pass him by not just once but thrice at least. Not a crippling flaw, but it does subtly belie the straightforward prose. Scalzi repeatedly hints at mysteries and questions, and has the guts to leave them unanswered (I don't think it's sloppiness) which again I found more interesting than problematic.
One such mystery, at least to me -- the CDF seems to recruit exclusively from American oldsters. All the CDF troop ships are named after U.S. cities, Perry only meets fellow (former) Americans throughout, and so forth. Where Heinlein's hero was a half-Filipino half-Argentine with a "Finno-Turk" master sergeant, Perry is from Ohio. In the novel, Scalzi mentions the Subcontinental War, in which America apparently won by nuking India (a development far less likely than gengineered super-soldiers, although that's just a nitpick) and states that Americans (except CDF veterans) aren't allowed to colonize the stars. (This is implied as a bit of a punishment for atomic misbehavior, but it predates the nuclear war.) Indians and Pakistanis and (one presumes) other Third Worlders can emigrate to the colonies without joining up; this is also explained as simple "fairness" since America is still prosperous and underpopulated, so the poor huddled masses elsewhere need colonial outlets. But the colonies are also depicted as essentially dominating extrasolar travel -- are they really not interested in highly skilled American engineers, doctors, or biologists? Unless they join the CDF and risk getting all those life skills blown up? Really? Perhaps it's all explained in the sequels, but it's weird that nobody in the novel thinks it's weird -- unlike the other mysteries, like how the CDF builds a beanstalk with no counter-weight, or what some of the spookier aliens are up to.
I don't think the all-American CDF is an extension of, or even a riff on, the "America as world sheriff" theme occasionally prevalent in the more testosterone-scented genres, but I'm at a loss for a sensible explanation from the material available in the book.
That said, Old Man's War is a good, solid pull from the Campbell-Heinlein flask, interestingly cut with some newer caskings. Well worth your $7.99, and your five-to-ten hours.