I'm glad that this Zappa recording is still available, but it's not a vital contribution to the development of either rock music or comedic theatre. The humour is, frankly, very teenage schoolboy -- i.e. strong sexual content, as it's called these days -- and only raises its interest level when making side-swipes at the cultureof the day (e.g. the Vanilla Fudge and the Edgewater Inn, Seattle).
The standard of musicianship is, as ever, high, when you can discern it. Sadly the recording quality is very low. Musically, Zappa was in some ways his own worst enemy: as soon as he had played a riff once, he was bored with it, so he moved on to another musical theme, to the frustration of much of the audience.
If you want a great Zappa live recording of around the same period, without the blatant sexual humour, but with Captain Beefheart and some outstanding rock music, and much better recorded too, buy BONGO FURY.