Great stuff! Watched the first four episodes. Burns does a good job of exploring the confluence of folk music and commerce. He spends more time examining the myths than digging through the roots; but for anyone who is interested original, historical recordings are easily available these days.
If authentic, roots music is your interest, I would advise checking out the Round Peak musicians, Piedmont and Delta blues, and more obscure musicians such as Roscoe Holcomb, Tommy Jarrell, the Mississippi Shieks, and Charlie Patten.