The delta handle and ergonomic throttle design.
Bright L.E.D. lit battery gage blinds at night. Seat will not elevate or lower, a must have to accomadate getting down to a toilet or up to modern high beds. A fixed seat height is really a drawback. Pillar adjustment is difficult on elderly hands with screw type locking handle. No rear lights is a safety hazard at night. Throttle speed control is not smooth but jerky.
I am 69 years old and have lost all use of my legs.