It obviously isn't "complete and utter" bullfeathers. There was slavery in the United States, and Americans were involved in the slave trade, and slaves were often punished harshly.
"Roots" does probably count as propaganda, though.
Would Haley's story had been published, and the subsequent movie been made, if he had traced his ancestor from Africa to say Brazil? Haiti? Saudi?
Would Haley's story had been published, and the subsequent movie been made, if he had been a white man and had traced his ancestor from say Scotland who had been sold as an "indentured servant" by the British government to the American colonies in the 17th century?
I have read enough about Reconstruction to know that events that happened in "Birth of a Nation" did happen. I wouldn't say that either "Roots" nor "Birth of a Nation" would represent society as it was as a whole and in context.
I saw "Roots" as a kid back in the 70's and I was absolutely convinced it was true at least until recently when I was reading one of the Destroyer series of adventure novels and the author implied Roots was fiction and gave some good reasons which made me think.
All these years I never thought to question nor challenge what I learned as a kid. As a society we really need to learn to question everything as Socrates thought his pupils.