This is an outstanding product. I purchased it as a gift for a friend and she is thrilled with it. She uses it at her computer and finds it far more comfortable than a regular chair in addition to the fitness component.
I am using this chair at my work desk. I have hip problems and the support of the ball keeps me from hurting at the tail bone when sitting for long periods. Love the back support, too. Only draw back is how low you sit to keep your legs in the proper position. If I was shorter, this would not work at my work desk.
I use my balance ball chair in my office all day. On even a well cushioned executive chair, I still feel lower back pain and go numb. With the balance ball chair that doesn't happen. The same is true in my car where I use a balance disk, especially on a long drive. I normally don't buy things like this without trying them in a store first but I took the chance and it paid off. They might want to make one that would be good for a child working at a desk.
In the short time I have used my chairs (i.e.,at home/work) my back pain has decreased significantly. They are very comfortable, and make sitting in the correct posture enjoyable. In addition, assembly of the chair was not difficult. I used my personal electronic pump to fill up the ball with air. Manually inflating the ball might be cumbersome, but I cannot objectively comment on this.