This is a fantastic head. I've had an Acratech Ultimate Ballhead for five years and loved it the whole time. The novel design means that it is more maneuverable than a typical ball head and that it basically never needs cleaning. It's true that certain positions require swiveling the head, but it allows for so much more movement than a typical ballhead that I don't see it as a problem.
Some reviewers have mentioned that it experiences creep, but I've never had that problem. It's always been rock solid for me.
I've started doing video work in the last year, and the design works really well for panning and other camera movements. Just loosen the ball to the desired tension and you're ready to go.