Haffner wrote this book for an English audience in late '39/early '40. His aim was to bring a native German voice to the debate and to educate the English on what was really going on in Germany.
His condemnation of the Nazi regime is harsh and unrelenting, which is to be expected. I do not know what the average educated English person knew of the realities of the Nazi regime in 1940, but Haffner wastes no time in educating his reader on the harsh inhumane brutality perpetrated by Hitler et al. Moreover, he casts the Nazis and Hitler in particular as swindlers and criminals, emphasizing the fact that they rule because they siezed power. The Nazi party according to Haffner must be destroyed in order to rehabilitate Germany.
He does not exculpate the German citizenry. He saw the Nazis as the natural result of the drive for empire instigated by Bismark in the 1870's when he changed Germany from a loose confederation of states into a reich. He also believed that Germany had to be utterly defeated so as to render the nation innocuous thereby destroying German arrogance and belief in their natural right to conquer, anything short of that and there would be another war in 20 years.
According to Haffner, there was a sizable element that was anti Nazi in Germany and that they faced insurmountable obstacles in trying to coordinate some kind of action. It leaves little doubt as to the horrendous and depressing situation faced by anyone who wanted to actively or passively oppose the Nazi party in Germany.
I found Haffner's attempt to elucidate and educate the English in 1940 very interesting. If I was an Englishman in 1940 and was dubious about the need to wage all out war and I read this book, I would have had my doubts removed. And I would have understood that the only acceptable end to the war would be Germany's utter and complete defeat and the liquidation of the Nazi party.
But it is obvious it was a rushed work as I am sure he wanted it to go to press as fast as possible. It could have used some more re-writes etc, but given the imperative situation facing England in late 1939, his haste is totally understandable. All in all, a great read for people interested in the period.