I bought this for my wife as she wanted to tone up her waist, hips, etc. She works in a manufacturing warehouse, so she is in decent shape.
The first time she used it, she had sore muscles around her tailbone area. She waited until it eased up and used it one more time. This time, however, she hurt more and ended up going to a chiropractor and a massage therapist. She won't use the board anymore as the massage therapist advised her not to as it is the worse thing you can do to tone up. She recommended sitting in an office type swivel chair with feet on the floor and swivel back and forth. She gets the same type of workout without hurting herself.
This cost me over $130 (for the board and office visits). I don't think the board is worth it.
Bottom Line: No, I would not recommend this to a friend