The "4x4" variant can go anywhere, on any reasonable and unreasonable slope (like 45deg), in any direction (not necessarily gradient). It's very hard to fall from it but not impossible. It can feel jumpy on hard terrains. Speed = 25km/h. You can drive handsfree, the UI is very intuitive. After 5 minutes you don't feel the machine anymore. Charged by a teapot plug (like a comp). It can be yours for about $7K.
The city variant - can be riden on sidewalks only [israel], but requires no license. Can be used instead of walking in any possible way, you can drive slowly with it into elevators, etc.
It has regenerative breaking (for descents and stops). Full charge time - a few hours. Max reasonable speed - 25km/h. Gyro sampling frequency - 100Hz. Min age to ride it in Israel - 16YO.
To try one - go to Eilat, call 077-2199906 to schedule a long segway trip to the birdwatching park. I asked about renting one - this would actually be a cool toy in Eilat, because a car there isn't very handy. They didn't sound too cooperative, the idea was kinda new to them.