Author: John Scalzi
It’s been a while since I’ve read hard sci-fi, and perhaps as long since I’ve read military sci-fi. Old Man’s War is both, and succeeds as both, at least as far as I can tell.
It is the story of a man who, on his 75th birthday, joins a galaxy-spanning military service. This is standard practice, and those who join: a) don’t know why only the old are recruited and b) know they can never again return to Earth. Indeed, no one on Earth knows any details about human extra-solar colonization, except that it is occurring.
It’s a good story, fairly well told. Data dump expositions are inevitable, I suppose, and are handled with only modest awkwardness. Plus, the data dumps contain new (to me; see warning above) sci-fi elements, so that makes them all the more bearable. The rest is fresh and exciting, with at least two characters you care about.
It is told in first person, which gets to me because almost all sci-fi seems to be so, now-a-days (except when it’s in an even more annoying second person; I’m looking at you, Charles Stross). But I’m sure you can get over that.