I purchased my Kingsong 16s a couple of months ago. It has been a new learning experience indeed. It took me about a month to become quite proficient riding the one wheeled EUC. I am now planning on purchasing the larger Kingsong 18L.
The downside to this EUC was the app. It was and still is awful. It took me at least a couple frustrating hours and several phone calls to Jason, at ewheels, to get it working. I have now switched to Apples iOS phone platform and I cannot get the Kingsong app to work. My alternative was the Darkness Bot app. This has worked fine so far with my Ks16s.
Overall, great first wheel and I would definitely recommend it anyone who may be thinking of getting into EUCs.