The Adrina Flat is VERY comfortable and soooo soft.  I wore these (I liked them so much I bought 3 more pairs in different colors) every day all summer long.  I have a regular arch and no problems with my feet, but I do have some back problems and these were like walking on air.  I also like the ones that change color in the sun...they are really cool!  When I first received these I thought they were going to be too small, but they stretched out in a few days and now actually fit a little loose.  No rubbing, no blisters, just a great fitting shoe!!!