I had a chance to ride the Mobiky 12" at Interbike. While I thought it was a cute gimmick; I didn't like it. They did have a 16" model too. I didn't get to ride it. I really think the Mobiky design is very appealing, but it's just too hard to ride. They had a few 12" designs the main difference was the gearing.
Love the way these bikes fold, but the ride put me off.