My son has a couple of pairs of these & I decided I'd like a pair as well.  The medium fits me nicely - I wear a 6 1/2 women's shoe.  My feet do get very warm in them after a while, but they don't sweat.  I don't usually wear them for long periods of time - I tend to put them on to take out the trash or check the mail.  They wash easily.  When I do wear them in the house, the non-slip tread makes it so I don't slip on my ceramic or wood floors.  They don't have actual soles, but that is what I wanted - kind of a 'bootie'.  Happy with purchase.

Update:  After wearing these for more than a month, I wanted to add some observations.  I don't know how many people this will apply to, but I have vericose veins in my legs that restrict blood flow to the extent that my ankles swell.  I have to be careful of what kinds of socks & shoes I purchase.  These little booties ride down below the part of my ankle that gets feeling tender, so they feel better than most shoes.  They also do not restrict blood flow in my ankles (I am small framed, so that could vary from person to person).  I'll also add, that while these feel great on my heated floors, the chill of my unheated tile floors comes right through these.  So, I would consider these to be like a sock for warmth - not like a shoe or most slippers.  Still happy with purchase.