I've seen these or "bikes" like them from time to time, though never this iteration in the flesh. I see two "issues"

1- no seat. Possibly the biggest benefit of a bicycle is the seat. That means that you don't have to support your weight, and 100% of your effort can go to propulsion.

2- rear steering. Normal front steering is like a weather helm, automatically and quickly bringing the line of support under your "fall". Rear steering first moves the bike out from under the fall before coming back under you (bike goes left before turning right). This makes the handling seem funky and unstable, though it can be adapted to easily enough. If you don't see the difference, you might if you've ever tried backing a car out from a close wall on the side.

So, with those two differences, I classify this more as a scooter or novelty than a bike. Since it's not that small anyway, I'd rather have a scooter, or small folding bike.

All that said, I wouldn't pass up chance to play with one of these if they came my way.