I went to the 1981 bike show, back when they held it at the Colosseum in New York City. A Japanese company had reinvented this. It was set up on a trainer, and the suit-and-tie-clad gentlemen invited me to try it. I pedaled it extremely hard, and it exploded under me, causing me to fall. I wasn't hurt at all. They were extremely sorry and embarrassed. I told them not to worry about me, and I also told them why I didn't think it was a good idea. They thanked me.

Basically the problem they think they're solving is the dead spot of the pedal stroke, where you're not applying much or any power. They replace it with the power portion of the stroke. It doesn't take into account the energy it takes to accelerate your leg from zero to the power portion nor the energy it takes to decelerate your leg back to zero at the bottom. Total energy expended increases with this design.