Yikes, that thing will not sell. The core demographic that would use it are the same people that want to look the coolest. And I can't imagine anyone cool sitting on something as dorky. Another good idea killed by poor design.
I think the Segway faced the same issue -- and an even simpler orientation for such personal devices, seated in a forward direction, is terminally uncool because it's so closely associated with the elderly and others with mobility problems.
I wonder, then, if units which are different for the sake of looking trendy could take off. In particular, whatever the safety issues, what if a personal motorized device expected the rider to face their body perpendicular to the direction of travel, like a skateboarder (able/cool), surfer (able/cool) or snowboarder (able/cool).
Would the rider then be sending a signal of 'fitness' even with their motor-assisted personal-travel, and could that then be the margin of approval that drives adoption where other units have failed?