This outstanding documentary of Robert Johnson reveals much. It shows, be means of people playing live, how great is the Delta blues and Robert Johnson music. I know from the beginning of my own efforts almost two decades ago now, and hearing what others things of it, that people often feel Robert Johnson for one is a bit Spartan sound. Sounds like dirt on a dirt road. Sometimes, one has to see these things live to really see and hear it and feel it.
I've heard of John Hammon before, but I didn't believe he could play. But, to some topics that comes up in the movie that I found a bit striking . . .
. . . the people Mr Hammond was able to find(and he finds some interesting ones!) seemed almost embarrassed to talk about Robert Johnson. His death by poisoning seems pretty clear, so the embarrassment is a bit over-worrisome imo; but, the interesting issue that comes up when discussing the blues and Robert Johnson back then for these people is that the music is devil worship. They say a bluesmen must have sold his soul to the devil to learn how to play like that. And indeed, Robert Johnson and other bluesmen(I can think of Peetie Wheatstaw who also liked to associate himself with devil and the blues) almost wanted to be associated with this folklore of selling your soul to the Devil to learn the blues. Robert Johnson wanted to learn the blues so bad so he can 1) stay off the plantation, and 2) get lots of women. It ultimately cost him his life of course.