When walking, these slippers are pretty comfortable.  The heel does tend to slip off if you go up on your toes (like reaching for something or, for me, climbing the stairs).  The problem, though, is that the cushion under your foot, which is very plump and comfy when walking, is so thick when your weight isn't on your shoe (like when you're sitting with your feet up) that there almost isn't enough room in the slipper for your foot.  Your toes start getting pressed up against the top of the slipper pretty hard and the heel falls off your foot with the slightest movement.  Overall, I'll wear the slippers while walking around my house, but when I'm relaxing in the recliner, I usually slip the heels off and partially slide my feet out to give my toes more space.  Also, the insides are comfy and soft, but allow good airflow so that your feet don't get sweaty, which is great.