This was down in Devon, and the Segways were vaguely off-road biased with two low pressure chunky treaded tyres. After the first half a mile of so (on tarmac) the instructor removed the speed restricters which I hadn't realised were in place; they were still definitely restricted even after that but I suspect only to whatever the legal limit is - probably 15.5mph like e-bikes.
First impressions - they don't feel quite as unnatural as you might expect from a device which must be constantly adjusting its point of balance. Manoeuvrable too - easy to spin on the spot. Took 30s or so to get used to moving off smoothly and braking to a halt.
After being derestricted we were let loose in an off-road playground, with just a couple of deep lakes to avoid
I was constantly trying to get mine to go faster by leaning forwards in different ways. Did manage to get a real wiggle on when cornering at max speed and fell off into some foliage but kept it upright so it didn't turn itself off. Going up and down some steep hills was interesting; weirdly it feels more unsafe going up because it seems to be programmed to lean you back slightly going down and there's never a feeling it'll run away with itself.
Overall, an amusing curio; glad I've tried one. I think you could have a nasty accident if you were racing someone and rubbed wheels because the tyres protrude and once you bounce a wheel off the floor, there's no innate stability. And they're not effortless; you need to put some work in to get speed out of them so with such a limited range and high price they're not a patch on an eMTB for getting around or range.