This is a very good story, and well told, even if ghost written.
Oddly, it casts the Duke of Windsor in a poor light, and indicates why, quite apart from the marriage question, he was a bad King. Who can read without wincing his account of how he abruptly cut short the presentations of debutantes to him at Buckingham Palace because it started to rain? This was the high point of perfectly harmless society ladies' lives, and he not only walked out in the middle, but caustically observes that he cannot understand why anyone was upset.
And then there is the peculiar passage where he says that he worked out that it would take nearly a month for bodies like the Universities of Oxford and Cambridge, the Board of Deputies of British Jews, and others, to present their loyal addresses, so he insisted on them all being done in one day, in one batch, because he could not be bothered to respond to all of them individually. Yet this was his job as a constitutional monarch!
A welcome feature of the book is that it stops at the moment of abdication. Although this means that he doesn't have to explain his conduct during the lead up to the war, and during the war (which is, however, documented in the Duchess of Windsor's memoirs), it does focus the book almost entirely on his upbringing as a Prince, and on the abdication, which are the most interesting things about him.
Well worth reading.