I quite enjoyed Festival Express, although I can't say I would have made a particularly good rock 'n' roller myself. Watching Rick Danko, Janis Joplin and Jerry Garcia laughing and singing together while utterly smashed may be historically interesting, particularly as they are all now dead, but it's not a particularly comfortable thing to see, any more so than being the only sober person at a party ever is.
This was one of those rare DVDs where the extra features were at least as important as the film itself, so in a way I'm glad I didn't see it in the cinema after all. The features doubled the length of the material with extra music performances and interviews which answered some of the questions raised by the film itself. Since the film was less than 90 minutes long, I'm surprised they didn't go for a longer edit - they obviously had sufficient material.
Apparently the rest of The Band and several members of the Grateful Dead decided not to travel on the train at all but made their own way from venue to venue, which seems to me to rather destroy the point of the enterprise.