These shoes work as advertised. I have had them for two weeks now, and yes, I feel the difference. I feel it in my calves, hamstrings quads and in my lower front core.  I usually do a lot of bicycle riding in the summer. I could not last summer because it was way too hot, so I have been looking for ANY way to augment my fitness taking into account my busy schedule. I found these and they work well. Especially if a lot of walking is involved. They say to only walk in these. I understand that. They work on a Balance board principle. To run with these shoes would be almost as bad as  trying to run in 1-inch spiked heals.  I wonder if I can use them while bike riding as the bottoms are still flat.  In any case, I am hoping to see the WM1100 out soon.