It might be worth a look, but having seen the ass-over-eyeballs attitude fairly frequently among a small group of young athletes who brought segways to a festival a couple of years ago, I'd guess that most people who need what's generally considered a "mobility assist" might be a bit brittle for the risks involved.
The Segway also flunks the "speed limit" imposed in many places where the public is permitted to use handicapped-assist vehicles. It's perhaps more suited to replacing a motorcycle than as a substitute for a wheel chair. (just a speculatively offered opinion)