I have one which I bought used in probably 1976 or so. I used it extensively for years doing rock, pop, banquet and show bands, theater, jazz, you name it. It works and sounds fine, but as a previous post said it is very heavy and unweildy. I haven't gigged with it for 20 years because, frankly, the newer amps and cabs work just as well, if not better, and are much more powerful and lighter to boot. It still gets played at home on occasion. I have the square magnet speaker on mine.
I heard a bassist at a festival using one for his "punk-grass" band a couple of years ago, it and he sounded great.
Hope this helps,
Dennis