If I could use a regular bike for anything more than getting me to/from the light rail (a few miles from my house) for trips to friends' houses on the other end of hte valley, this type of drive would at least allow me to ride a regular bike, which I can hardly even do nowadays.
If it werent' for it's cost, it would actually be pretty good for most people that just want an assist on their bike, that arent' looking to be moved around without any effort. .
(typically I need much more of a bike to do my normal trips, which include hauling large or heavy stuff around, and this drive would be woefully insufficient for that!)