I ordered a M as I am between a S and M.  I am 5'6" and 135#.  I thought I would want to wear a light sweater underneath.  In retrospect, I think this sweater would look better on me in a S (with no sweater underneath) and I may exchange it.  The sweater itself is very well made and not cheap looking.  I haven't worn it yet but it looks like it will be very warm!  All in all, whether I get a S or M, I know I will keep it because it is very stylish and warm!  I purchased the eggplant color.