I got 2 pairs of these several years ago for Christmas. I don't know if they're the old type or the new type. (as mentioned by the one-star reviewer.)
I wear them in place of slippers, they're very comfy. The heel seam on one of them has gone out... I suspect that if you get too small a size this will be more likely to happen, because fleece doesn't have the structural integrity to stand up to constant stretching. My feet are about a men's US size 11 and I have the large, which fit comfortably and aren't too tight or too loose.