3 weeks in and I'm still loving these slippers.  Definitely opt for a whole size bigger than you normally wear.  I wear an 8 1/2 size shoe so I ordered a 9 1/2 pair of these slippers and they fit perfectly.  The velcro strap is strong and can be fastened loosely or tightly.  Keep them loose if you want ease of slipping on and slipping off.  You can still walk properly and comfortably even when strapped loosely.  The cushion on the inside is just okay, nothing to get excited about.  It isn't  a thick pile of material and has a tendency to shed initially.  You'll find pieces of fuzz on your foot when you take your foot out of the slipper.  The verdict is still out on the quality of construction but so far they are holding up (3 weeks in).  Definitely only wear them in the house and don't wear them while you do your exercises or strenuous cleaning such as vacuuming.  They are comfortable slippers and NOT indoor performance shoes. You'll want to limit the wear and tear on these to just casual use indoors to keep your feet comfortably covered.

You can wear with socks or without but like other reviewers have noted, your foot will sweat when bare.  I step into them barefoot if I get out of bed in the middle of the night and in the morning after I first wake up.  The soles are vinyl and make for a good non-slip experience on smooth floors.  At this point in time my recommendation to buy is a strong one.