There was another recent thread where I expressed my opinions.

What I notice, around here, is that it is very rare to actually see one- like once in 5 years I think? Yet, they crop up on Craigslist pretty regularly, where they are invariably advertised as the best thing since sliced bread. So from that, I get the impression that the idea really appeals to people, but the reality must sort of suck. So people buy them but don't really use them.

The main drawback I see is the noise- about like riding a chainsaw.

Somebody up there mentioned the worst of both worlds. You get the exposure to elements, the slow speed, the hazards or bicycling, but without the exercise. So if you want to go slowly in the freezing rain while you get run over, without being healthy, they're just the thing. But seriously, I ride a bicycle, got nothing against riding motorcycles, but I'd ride all kinds of little motorized scooters before I started sticking a motor on my bicycles.

One other thing is that it seems people invariably stick these on the crappiest bicycles with the crappiest brakes, too.