I love it. And my back does as well.
Now that I have had this for six months I do have one suggestion for the distributor. Humanscale should ship a patch kit with the stool. Failing that, they should post information on how to repair a puncture.
Over the recent holidays I moved my stool next to my grandson's model train layout on the floor. A bit too close as it happened. One of the track cross ties punctured the inflatable base. My calls and emails to the Humanscale office in Colorado asking for help got no response. After two days, I tried bicycle inner tube repair patches. They did not work. Finally I took my stool to a local automobile tire shop. They patched the puncture with a large black patch. Now black would be OK if the stool base was black. However it does not look so good on a red base.