At 50yrs old I bought a half bike, I cant ride an ordinary bicycle due to pelvic pain.
I really enjoy going out on the half bike, you certainly get lots of attention, almost all very positive. Its harder work than a normal bicycle, probably half way between running and cycling, its great on tarred roads but its more difficult once you go off road, certainly no mountain bike terrain, you need to be more careful of pot holes and bumps in the road than you would an ordinary bike and a little more careful with the braking when going down hill fast, its also hard going on steep up hills but its great for keeping fit. Initially its difficult to ride but stick with it because it will be worth it. Give yourself a couple of days practice and you should be getting up to it. Look at it like you are learning to ride a bike all over again. In my opinion the half bike was quite expensive when i bought it but occassionaly there are deals out there and it does seem well put together.