I saw Joe at Fillmore East and again at Woodstock in the summer of '69, during his first U.S. tour. At the Fillmore, he opened, IIRC, for Jefferson Airplane and blew everyone away w his singing AND his unusual gyrations, which I always interpreted as "spastic air guitar". Wikipedia says "Onstage, he exhibited an idiosyncratic physical intensity, flailing his arms and playing air guitar."
What a talent. It was great when he finally got sober and was able to return to the make music on a regular basis. Considering how he partied in the 60s and 70s, it's pretty near a miracle that he lived to be 70 y.o. R.I.P.