Comparing this novel to Robert Heinlein (particularly Starship Troopers) is fairly apt. In both cases, we have an interesting central concept, some interesting situations, some interesting tech, fast-paced story telling, and an almost complete lack of "meat". It's the sort of science fiction novel that is fun to read but would rightfully be considered "junk" (as in junk food). Nothing wrong with some candy once in a while, but too much of only this stuff will rot your mind!

Having also read Scalzi's "Lock In", I have read his first published novel and his latest published novel. It is interesting to note that Scalzi really does not grow as a writer from this first novel to his latest outing. In fact, the main difference is that Old Man's War has a considerably more humor than Lock In. This is not necessarily a condemnation, since it demonstrates a sort of "if you like one book by Scalzi, you'll like them all!" Of course, that also means this is not a commendation either. It is what it is, Scalzi writes, in part, to entertain... and that is what you get.

Now, having said that, I was impressed by the spiel of one of his characters regarding multiple universes. Particularly the following: "the universe you're in- the universe we're in right at this moment- is only one of an infinite number of possible universe whose existence is allowed for within quantum physics." Emphasis is mine to point to the fact that though Scalzi does not use a lot of highly complicated scientific rigmarole, he does make sure that the reader understands the concept of "boundary conditions!" I find conversing about the multi-verse in real life irritating because many people are not... sophisticated enough, we'll say...to take this into account and assume that infinite universes mean a Harry Potter type universe exists! NO! That's complete and utter garbage! Something HAS to be possible before it is a POSSIBILITY!

Originally, I had awarded this book three stars, but after raising my blood pressure slightly with that rant, I've decided to award this book an extra star for getting something very right! Do not spend it all in one place, Scalzi!