Ok, I slept on this one for waaaaaaaaaayyyyy too long.
There's a LOT of music going on here, some of it totally what you would expect from a "musical", some of it not...but Joe Williams as the devil come to earth as John Henry who purports to lead his people to "the promised land"...and all that comes with all of that...suffice it to say that there's more meat here than I would have expected, although not a lot (if any) "jazz", which is ok by me, actually.
and Joe Williams RULES on this thing.