In my best KY gobblety gook it’s both harder and softer. He removes some original foam, adds a layer of firmer foam and a top layer of memory foam. I’ve read tons of great reviews but it’s not for me.
I took it off today to get good pictures, it does have more seam wear than I’d noticed, it is an 80,000 mile seat. To look at it you can’t see any difference after he’s done.