fantastic!
After sitting for three days at a conference in March, I developed severe sciatica.  Stretches, other techniques helped greatly, but it is still a bother with all the sitting I do at work (including lots of vehicle travel).  Ordered this 2 weeks ago, it felt good right away but after a week of use most of my pain was GONE from sitting at home.  I have travelled this week  to the same location of the March conference, and used the cushion in the car for the first time and also on the conference seats.  It is fantastic--it is actually kind of fun in the car, sort of bouncy but very comfy with no leg pressure problems.  On the chair, it is like sitting on a plush, comfy chair. it feels absolutely great.  I'm going to order a second one to have my husband try it, as he has terrible back problems including a failed back surgery.  I will let you know how that goes.  if he doesn't like it I'll take the second cushion to the office to use on my Aeron chair.
Rating: 5 stars