The halfbike is quite an achievement! The build quality is excellent and riding it is a lot of fun.
I started looking at it because I am suffering of low back pains after holding the same position over an extended period on my regular bike.
Riding the halfbike is a great workout if you ride it on longer distances and, given the upright position, will not create any pain, just general fatigue.
I use it sometimes to commute to work in place of my folding bike (in combination with trains).
The size when folded is a bit larger than my folding bike but there is nothing critical.
Sharing the road with cars is not an issue but will require more concentration than a regular bike. The front break is efficient but more anticipation is needed.
One advantage is that drivers are slowing down because they try to understand what is passing by in front of them :)
A nice improvement would be to add more speeds. I took the 15t sprocket, which is nice for flat terrains. Going up hills in a city like Brussels will get you a bit sweaty. But, as always, the more you practice, the easier it gets.