I actually think that it's better than the Segway for making you slightly shorter. One of the problems with the Segway is that the increased height (and width) makes you so conspicuous as to practically be flaunting your use of it, and how independent you are from the lowly ambulating masses.
Whereas someone riding a Vespa can still come off as cool. (Though they'll immediately look silly next to someone on a Harley.)
Well, yes. Someone sitting lower than others around him/her is not necessarily bad: think driving a Ferrari vs walking down the street. But this thing does not look cool. It looks more like you are somehow incapacitated (I think some other comments mention knee injuries). Even a hover chair from the Austin Powers movies would be better. Jetpacks would be ideal.
Whereas someone riding a Vespa can still come off as cool. (Though they'll immediately look silly next to someone on a Harley.)