It's working well but has taken several days to form to a level ground. The problem was that it is shipped to us in a box with the mat wound up in a long oblong shape bundled by bands to keep the oblong shape in place. When opening the box it quickly became apparent it was going to take a while to get this to flatten out. Ultimately it did and it's working fine but I wonder if there might be a better way to ship it.
Reasonably pleased as I remembered trying the display chair. The backrest and the " up and down" seat level work just fine however I am disappointed that the seat itself does not tilt forward. A seat tilt control is rather important for my comfort.