The Halfbike can handle light off-road but keep in mind that it's a city child. So riding would feel best on nice and smooth surface. Well packed dirt roads are also fine but don't push it into the real bush.
Personally, when going off-road, through potholes or any other uneven terrain I try to keep my hands as relaxed as possible. This takes tons of practice but keeps me in balance when I hit something uneven.