I love this slipper and the sheepskin lining in the interior.  When you first get them they are very comfortable.  However over time the sheepskin gets matted down and loses some of its comfort.  Also, the inside sole wears out on the heel and ball of my foot (see attached pic). I wear these all the time when I'm in the house during the cold weather months and I work from home.  As a result of this I have to replace these every year.  Replacing them every year is a small price to pay for this slipper with how often I wear them and how they feel.  I am going on my 4th or 5th pair this fall.