With this Scalzi brings his "Old Man's War" sequence to a finish (though it appears that his latest "Zoe's War" is also set in the same sequence, just giving a different perspective on the action).
Old Man's War was a fine example of military S. F., giving a fresh perspective. However the two sequels seem to have progressively run out of invention and I think the author is right to now draw a line, at least for now, under the sequence to look elsewhere. Because it offers little new, I was disappointed by it. It is competently written and concentrates on the politics rather than the military action in this Universe.
Basically, the protagonist Perry and his wife, recently retired from the military and put back in true human bodies, become colonial administrators and lead a new colony. The Colonial Government it is as duplicitous and questionable as it has emerged as being earlier in the sequence.
If you have read the prequels you you will probably want to read this to see how it pans out. If you have not read them, do not read this with out having read the earlier works. Old Man's War is a must read for anyone who likes military SF. Its successors do not reach that high level of gripping the reader. Hence my rating, though I stress there is nothing wrong with the work, it just falls short of its predecessors.