I was shopping at Office Max one day when I saw this odd looking thing in the chair department. I didn't know what it was, but curiosity got the best of me, so I had to go check it out. After figuring out how to sit down in it and position my knees, I thought it was pretty cool. The cushioned seat was fairly comfortable as was the knee rest. I liked that it had casters on it so that it would be easy to move around, although to move around in an office, you'd have to unfold your legs out of it, put them on the ground, move around, then re-position yourself. Probably once you got used to it, it wouldn't be so awkward.
As far as supporting my back, it felt pretty good at first, but I wasn't sure that after a while of sitting in it if it would really be that much better than a good office chair and I was pretty sure that my knees would be feeling the pressure after a while.