I bought these a few weeks ago as I have chronic cold feet during the winter.  When I first got them I was ecstatic about how comfortable, warm, and well designed they seem to be.  I wear them only indoors, on very smooth floors (wood, markble, rubber), and the non slip grip material on the soles have worn completely smooth, making them quite slippery and hard to move around in safely.  The soles have also compacted and they are not nearly as warm as they were to start.  I tend to wear them when I am relaxing around the house....and they are ok for that, but am disappointed at how poorly they have held up (I am not hard on clothing).  I would STRONLY dissuade anyone who has difficulty walking or is prone to injury from falling to purchase these - I have nearly gone flying to the ground a couple times because of the poor construction.