The Idiot’s guide is not really an instructional book, although there is some riding instruction in it. It covers a wide range of motorcycle topics (street riding, dirt riding, protective gear, history, maintenance, touring, racing, clubs, etc.); none of them in great detail, but a really good overview of everything motorcycle.
That’s why I would strongly recommend it for someone who’s just getting interested in motorcycles.
If I’d read “Proficient Motorcycling” from cover to cover before I’d gotten on a motorcycle for the first time, I may never have gotten on a motorcycle. I found some of what’s in it quite disturbing when I realized just how many things *can* go wrong on a motorcycle. I was riding very gingerly and with trepidation for a week or two after reading it. An essential read though IMO.