Tom Munro's review has an excellent summary of the arguments in the book, so I shan't add to it.
I would encourage students of the Second World War to buy this book. This is a rare book that looks at the war entirely from the economics perspective, resisting the temptation to discuss military matters as many were wont to do. This results in a remarkably clear picture of the homefront picture.
This is important as it helps to address some of the myths of about the Second World War, especially with regards to the German economic performance vis-a-vis the other economies. These myths gave rise to puzzles that were usually not addressed.
For example, if it were true that the Germans lost because they had a smaller economy than the US, the British Empire and the Soviet Union, and the Germans knew this, then why did they launch a war in the first place, not against one, but all of the great economic powers? This was usually explained unsatisfactorily by the 'irrationality' of the Nazis.
As the author demonstrated, there was logic to the madness. The Nazis operated under a flawed assumption about how economics work, and believed that it was only by having a large economy that Germany could compete - and survive as a great power - against the other great powers, especially the United States. Thus, by this logic, Germany had to expand and conquer to build up its economic strength. The more likely war was to become with the US, the more Germany must throw everything into a 'do-or-die' gamble to grab enough economic resources to survive.
This is not a wholly novel argument, but I have never seen it argued so clearly and backed by so much economic and historical data.
The same could be said for the genocide of the Jews and other peoples by the Nazis. On the surface it seemed nothing but insane cruelty and barbarism. Yet again, Tooze demonstrated that there was logic in the madness, that once again, the Nazis, operating from their flawed picture of the world, chose a perfectly rational solution by their light. As food was one of the most critical items in shortage in the Nazi war economy, and enough must be provided for the German people, then the lesser people must be starved or killed outright. The less worthy would be killed off earlier, while the more able would be worked to death as slave labour. It was a perfectly economical solution in Nazi eyes.
Finally, I found Tooze's examination of "Speer's Miracle" to be absolutely enlightening. I was under the impression that Speer's efforts after the death of Todt helped to economise the German war effort and pushed it towards greater productivity, allowing Germany to survive longer. The author showed that this was not the case, that most of the measures attributed to the productivity increase was put in place before Speer's appointment. What happened was Speer repeated the traditional pattern of Nazi war production, where much resources were at first pump into one area, then another, according to perceived needs of the Nazi leadership. Thus, resources were first flooded into tank production, then withdrawn and poured into U-boat production, then finally, pulled again and put into aircraft production. This resulted in short bursts of great productivity in one arm or the other. But Germany never really became stronger overall, and Speer's Miracle was nothing more than a facade.
To add to this, Tooze launched a devastating indictment against Speer's claim that he did not know about the Nazi genocide and slave labour programmes, pointing out that much of the labour used in Speer's armament programmes came from concentration camps or slave labour camps.
In the end, the greatest strength of his book was the straightforward assembly of many facts and events into a single timeline showed clearly the mad logic that drove the Nazi relentlessly towards war, and then equally inevitably towards brutality and genocide.