Got an XL which usually gives me room for a sweater.  But the shoulders and arms were quite tight even without a sweater.  They have full insulation in the sleeves which is nice but makes the sleeves feel too tight.  Didn't think an XXL would solve the problem so I returned it.  I do have pretty broad shoulders but haven't run into a problem like this before.  Otherwise, a very nice coat and I would have been quite happy with it if the fit were better