At first glance the halfbike looks like a mix between a bicycle and a scooter, but looks can be deceiving. It feels different enough from both.
Riding the halfbike is a unique experience, and one where knowing how to ride a regular bicycle does not help you learn. The key is that your hands and arms are not used just to steer and control the halfbike, but to some extend to power and stabilise it. Your core is much more involved, especially your obliques. When you press on the pedal, you must counteract by pushing with your hands in the opposite direction, and it's easier if you do it before you put your full weight on the pedal. This results in a great workout.
It's funny how almost everyone trying for the first time fails to ride for more than a couple of meters. However, with practice, there is a certain elegance when you see an experienced halfbiker twisting their body slaloming by invisible obstacles, gliding on the asphalt like a fish in water.
This does not come right away, but there are a couple of adjustments that help. Adjust your posture so you're slightly bent forward and pull your hips back in order to shift some weight away from the knees. When you turn or stop, you should lean to the side or to the back respectively to counteract the momentum. Also, at least for me it's a bit easier if I lean on the handlebars instead of trying to pull them when I try to stabilise the halfbike on every pedal push.
There is something which is more difficult than it looks like it should be- riding when the road is slightly inclined to one side. Since the angle of the back wheels relative to the surface determine how you turn, this means that going straight requires you to hold the handlebars parallel to the road, so slightly at an angle, and there's pressure to turn.
One thing I still don't trust is the brakes. Due to the high centre of gravity it's not safe to brake the front wheel so the only option left is to brake the rear wheels. This is not very efficient and at least on my halfbike produces a screeching sound as the brakes temporarily lock up.
Still, overall it's a very fun experience, it's portable and usable, and I alternate commuting with my bike and halfbike. While the halfbike will not replace the bicycle, it has its place and I have no intention to stop using it.