I think it's a great idea.. Design it a little further and you get similar performance and probably better all-weather handling than motorcycles. Make it street legal and give it somewhere to add hard bags, carry a passenger comfortably, make it look a little less funky with the body styling, and you'll have a nice alternative to a car or motorcycle.
Maybe it'd be a nice alternative to people with less balance or with disabilities, or just people who think it'd be similarly practical without the fears of it tipping over in a parking lot..
I guess the real problem with would be visibility.. It looks lower than most motorcycles and might be harder to see by some people in a quick glance..
Ah well, just because it's not a motorcycle doesn't mean it's inadequate as a mode of transportation or just to have a lot of fun on.
Just my two cents..