It's definitely weird to ride -- I would ride it on a commute of more than a few miles. It's less stable than a real bike, but not completely unstable. e.g. I can fall of curbs but can't jump up them.
Most body parts are specialty, not the brakes system, I believe.
It meets its design goals very well: - Internal brake cables and quick release mean it folds very fast and doesn't get tangled up. - It can be rolled around when folded so you don't have to lug it. - It stands tall and thin so only takes the space of a small standing passenger on transit.
Answer honestly. Would you ride the Strida downhill at a 30 degree incline with a serious curve at the bottom without using the brakes, like you would a mountain bike? How about at over 15 miles an hour [like a racing bike]? A good folder should be able to do both easily.
I'm not trying to imply it feels like a weirdly shaped mountain bike. I'm saying it does its particular job very well. The seating position and narrow handlebars definitely preclude it doing anything other than getting you from the train station to work on urban streets.
I have a real bicycle, too for, well, actually riding a bicycle.