True enough, but there is enough fact twisted and mixed into it to make it highly pernicious, and there are a good number of people (one of whom cornered me and nearly killed me with boredom at the feed store some time back) who believe that there is a str5ong factual basis for what the book presents as fiction.
I have argued with people right here on FR who have stated flatly "The book is fiction, but the history in the book is fact."
Of course, all they had to back up the claim was the book itself.