The concept works quite well if not for the very soft sole material.  Not only do your feet rock easily in a natural motion front to rear, but because the sole is so tall and squishy your feet roll side to side also.  It's like being on ice skates to a degree, you have to consciously balance your ankles side to side.  This could be hazardous if your ankles aren't in good shape.

The other thing is that the inner lining is made of a very grippy rubber type material.  As you slide your foot in it tries to pull your socks up your feet leaving then stretched against your toes.  When you pull your shoes off, it takes your socks off for you.  Maybe this will get better with use.

I do Tai Chi and these are exceptionally comfortable for those movements.

There has since been a class action lawsuit against Sketchers for making claims that could not be substantiated about these shoes.