LOVE IT LOVE IT LOVE IT. Yes, it does work the core muscles, but for me, I first bought one for work because I was sitting in front of a computer all day in a chair that didn't really fit. The typing was worse as the keyboard could not be placed in an ergonomically correct place. Once I got it, everything was better. I then purchased a second one for the backless stool I sit on to sew. Yet again, LOVE IT.
Laurie