Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Great concept, but ....

it's a brick-hard surface to sit on for any length of time. It helps in rising, which is what I was most interested in, but I quickly found out that it's really hard to sit on. I pillowed it, no help. Pulling it under me when I wanted to stand was out of the question. I weigh 235 pounds and set it for that range, but promptly found out that the amount of force needed to get the thing to lower at that weight range was more than I could comfortably generate. In the end, I sold it. Not for me.