Yeah. I sure was disappointed in this author. If one is going to write and sell a book as an historical work, then one should stick to the subject. About two thirds of the book was taken up by all sorts of stuff having only a tangential, if any, relationship to the original subject.
Unfortunately a lot of historical books are like that.
To an extent all authors do put their slant on their work but the good ones are honest enough to say it and also mention other people's point of view.
The bad ones are those who present it as fact and leave it at that I think many history books in schools are like that.