There are ugly warts talked about in that book, but they fit. Marx was a madman, a foul madman...I;v emet smelly intellectuals just like him...it's good to know the personalities behind the ideas. After all, the Personal is the Political, as they say.
It's been some years since I read it, but I am quite sure I remember Johnson going on at length about Russell's sex life, his halitosis, all this other stuff that is, while interesting at the gossipy level, not really an engagement of his ideas.