Whether my expectations were too high or not, they were disappointed. I'll admit that when it was dropped in the bath it fizzed ... I'm sorry, I mean phyzzed. I won't deny that it made my bathwater change colour - a dirty minty-green colour. It even made my bath smell a little earthy. But, while it was pleasant to lie in some differently dirty water, smelling a slightly different smell, I'm not sure that really added much to the standard pleasure of a hot bath.
I lay in the bath for a bit, then the water got cold, and I got out again. The remains of the Geo Phyzz were washed away down the plughole. Three pounds really doesn't go far.