Honestly, seeing them zipping around everywhere they look pretty good on the face of it. The advantages seem obvious:

• Save time versus walking
• Quiet
• No effect on local air quality

The main issue is them colliding with pedestrians, but (similar to bike lanes) that's a thing town planners should deal with by creating the right environment.

I'm willing to change my view if people tell me good reasons they are bad.

Yes, there is more environmental impact than a bicycle, but not than an e-bike, and they seem to be good for people reluctant to cycle.