I have had this pumice stone for quite a long time now - over two years, for sure. It has been a terrific purchase and the pumice is still going strong. It was quite rough at first, as expected, and has smoothed out a little over time, but not to the point where it is ineffective. It is still quite rough! I buff my feet with it last thing in the shower, and it keeps my feet continuously smooth. It also stays clean and is very affordable ($2.50 currently, and I got it at KMart). I trust this stone, as it has worked so well for so long, and would absolutely repurchase.
If I don't take care of my feet every day I develop really hard, hurting calluses underneath my feet. I've tried a lot of different foot files in the budget class, but non works quite as well as this foot smoothing stone.
It is recommended that you use it after having bathed your feet, but I find it works much better on dry feet, before the bath. Just go in circles where you want to rub the dead skin off, and your feet will soon be baby smooth.
The negative aspects is: it becomes dirty quick, hard to clean and wears down easily. Nice to look at, great that is is made from recycled materials, but frankly I prefer other foot tools.