the problem is that the place where the top part attaches close to the heel is set in too far.  You end up walking on top of where they insert into the sole which feels like a prominent 'bump" and making it very uncomfortable.  Unfortunately, I  had them sent to my daughters house and by the time I got there is looks like its too late to return.  I still will try but it doesn't look good so far.
UPDATE: Amazon resolved the return problem for me and made a return label.  Love Amazon.