Derek, I've used it once (I only bought it the other day).
I always knew that that the Jo Sonja rance was the acrylic medium with coloured mica in it (Chestnut is coloured acrylic with Mica in it).
Well this stuff is like Jo Sonja's range, but much thicker, almost a paste, so far I've just put a thin coating over another colour, and it certainly gave a great effect. Next I will try to mix some other colour into a little of it and see what that does.