This can be read as a novel, or as what it is: a collection of four connected novellas. It's also a direct sequel to the similarly-constructed The Human Division.
"The Life of the Mind"--Rafe Daquin is a pilot on the Colonial Union freighter Chandler, when it is commandeered for a special mission by the Colonial Union's Assistant Secretary of State Tyson Ocampo. In short order, most of the crew is dead, Rafe is a brain in a box installed in Chandler, and he knows a great deal about a conspiracy aimed at destabilizing both the Colonial Union and the alien Conclave. Scalzi very effectively gives us Rafe's experience of waking up and realizing that he can feel nothing physical. Even his terror fails to produce normal physical effects. Then we experience with Rafe his discover of what's going on, who's behind it, and what, exactly, are his opportunities to do something about it.
"The Hollow Union"--Secretary Ocampo's carefully doctored report, as well as Rafe's undoctored version, have both been released and beamed to as many places as possible. It's wreaking political havoc in the Conclave, and Councilor Sorvalh has to help General Gau maneuver through the chaos and keep the Conclave together--if that is even possible. This is a very nice exploration of the twisty, complicated politics of the Conclave, but also a wonderful character study of Sorvalh herself.
"Can Long Endure"--Colonial Defense Forces Lieutenant Heather Lee and her platoon get a series of assignments crushing rebellions and attempts at secession from the Colonial Union by various colony worlds. Mostly, it only takes Lee and her own squad. As the problems get worse, and bigger, and they have to kill CU civilians who aren't part of any big conspiracy, but just frustrated by the admittedly deceptive and duplicitous Colonial Union government, they start to wonder if they're doing more harm than good. Lee in particular has to do some serious soul-searching and make some critical decisions.
"To Stand or Fall"--Our old friend Lieutenant Harry Wilson, who has had smaller roles in the earlier stories in The End of All Things, finds he's in the middle of the mess created by the Ocampo report and the Equilibrium conspiracy, and if he, Schmidt, Abumwe, and the rest of their team don't create a solution, they're facing the possible extinction of the human race. It's not that Sorvalh wants to commit genocide; it's that the maneuvering of the Equilibrium, and the Conclave's internal stresses, may leave her no choice. This is a dandy visit with some of the most familiar characters from The Human Division.
It all hangs together very well, and moves the overall story of the Old Man's War universe forward in useful and interesting ways. Scalzi deals with the moral ambiguity of the Colonial Union, evident even in Old Man's War, with subtlety and clarity.
I think this is best considered as a set of four novellas, rather than a novel, and that's probably how I'll approach it when Hugo nominating season comes around.
I bought this book.