Fucking amazing; I'm so glad I have the tape (even if I can't remember how the hell I came by it). It's the Grateful Dead at their peak, or one of them.
Not so much psychedelic anymore, as a band having just found its way back to rock 'n roll roots and now deciding it wants to be elsewhere. The tempo is faster, more driving; the jams are tight - you'd almost think, rehearsed. Jug-band meets jazz. Europe meets Africa, by way of French North America.
For an hour and a half, if you let it, the music will take you away to another world; a secondary creation, perhaps, but a Creation nevertheless, whole and entirely self-consistent.