Just tried a Bird for the first time, in Mexico City of all places. (Kind of symbolic that innovation would be embraced more avidly here than in the hand-wringing cities I've lived in the US in the past few years.)
1) My daughters (7 and 10 years old, I'm sure this violated the terms) had such a great time riding it back and forth that we spent over an hour, just on one block.
2) It was super easy to ride and I felt very, very safe. My daughters got the hang of it quickly. They had a few close calls with pedestrians, but they're kids. Kind of made me resent the adults who crash into people and ruin it for the rest of us.
3) The same speed felt a little scary on the scooter that would feel completely normal on a bike. This makes me wonder if I'd ever use one for commuting if a bike were available.
4) It seemed like the highest speed was unnecessarily fast. I was surprised it goes that fast; setting the max speed a bit lower would make me feel better about everyone else riding then.
5) The price is great, and I could try it for a buck. I love paying as I go without having to worry about subscriptions and such. The least you can possibly spend on Citibike is like $10 which I think is exclusionary and also the wrong upfront pitch.
6) the brake felt stiff and hard to reach, even for my big hands. My daughters could barely pull it at all, and it didn't seem to have anything wrong with it.
7) The wheels are just big and bouncy enough; it really rode well on CDMX's cracked sidewalks.
All in all, an amazing (and belated) experience! I hope the Boston area gets these.