This is a military SF story set in an almost dystopic future. Without going into many details, it sets up a political situation which seems unlikely, but not wholly unbelievable, and posits the notion that, given technology to effectively make old bodies young again, old people make better soldiers than young ones, based on their general life experience. It's an interesting notion, but the novel doesn't really explore it much; mostly it just follows one old man turned warrior through a series of fierce battles and other dangerous situations. (In fact, the actual events in the novel seem to give more arguments against the old soldiers than in favor of them.) I know nothing of battles or military life except from reading about them, but I find the battles here exciting and believable, and the military life outside of the battles unusual, but more pleasant and sensible than any description I've read of real military life or most of fantasy or SF military life. There is some actual SF speculation in the area of direct brain/computer interfaces which actually seems to make sense. But mostly, this is a story about shooting and blowing up the nasties before they can do it to you. It's short, easy to read, fun, and in places laugh-out-loud funny.
Not great literature, but a good read if you enjoy reading about battles. 8 out of 10.