These flats are most certainly the most comfortable flats that I have ever worn.  It's like walking on a bunch of little pillows.  Most flats are hard to walk around in all day because they have such thin soles.  These flats have an insole that is extremely cushy and has a ton of arch support.  I want to buy them in every color! I am usually inbetween 8.5 and 9 but I got these in size 9 and they fit me perfectly.  There was no rubbing on the back of the heel and they stayed on well because there is a little elastic near the back heel to help with that feature.