I have three of them. One at work, one in the car, one at home. Love it, love it, love it. I actually credit it for being able to move around as well as I can.
Having said that, you will either love it or hate it. Are you attending a quilting retreat any time soon, because probably someone will have one and I'm sure will let you try it. No matter where I go there is someone who asks if they can use it for a little while. I think about 25 percent love it. The remainder hate it. If you have an exercise ball and sitting on it gives your back some relief, I say get it now, but if you aren't sure try to borrow one for an hour or so and see if it helps.
amh