This Muk Luk is every bit as comfy as it looks.  It is a breathable knit but warm, and the sporty soles make it very durable.  The Large size I ordered is actually larger than I would ordinarily buy--I wear an 11 shoe and 11.5 sport shoe, so 12-13 is big--but it is not too big, so I guess it is sized somewhat small.  Bottom line:  great buy.