I own one, but never did manage to get much fluency with it. The build quality is good, though keeping it positioned in your hand right is tricky. I hold it with the bottom on my thigh so it doesn't slip down. The mouse joystick isn't analog and therefore basically useless.

That said, the ergonomics of it are stupid amounts better than any keyboard. You can just wheel your chair back a bit and sit however is comfortable. Changing position while using it is much easier too since you're just holding it in your hand.

I should get back to practicing on it I think. The advantages would be enormous.

I used one of these for a few months. I used it to write while walking around the mall or other mindless walking. It was pretty cool. I'll probably break it out again, was difficult to use for programming because lots of characters require custom chords I never got to making.