Has anybody used it, does it work, is it better than an orbital buffer
Two different tools.
Clay bars are highly effective for removing contaminants off of paint and helping to provide a shiny finish. However, done properly they are labor intensive and require hours of work.
I clay bar my personal cars once every couple of years but that is it. My shop cars/customer cars get clay barred and waxed before delivery. My detailer is worth every penny too because that is not what I consider a good time.
Clay bars are meant remove stubborn debris that gets embedded in the paint.
Yes they do work, but it's a lot of work for not a very noticeable difference. I don''t use it, because I don't drive show cars.
Orbital buffers are for (surprise) buffing up the paint (taking out light scuffs and scratches). Totally different purpose.