They are great and I used to see them buzzing a round here and the surrounding towns. I guess the majority of the people riding them did so in an jerk ass fashion and people complained so much that the local municipally banned them and you don't see them anymore.
About once a year there is a local rally of the things that swoop the local towns in packs of 60 or so thumbing their noses. It is really cool to watch. The few times I have seen this happen I have always been in a car so never followed.
I owned one that was given to me and after fixing it up I realized that I no longer had the good reflexes to safely maneuver the contraption and actually got 125.00 for the dad blasted smelly conniption .