Normally I wear a size L in most everything (I'm 6ft/195#) but I read the reviews cautioning to order a size lower. After I did some measuring,the size L sleeves would have reached to my knuckles, I ordered the size M.
The fit at my shoulders when I wear a suit coat underneath is fine, though my sport coats are a tight fit and make taking the trench coat on & off harder.
But with a sweater and a base layer it fits great and that is how I will normally be wearing it so I gave it 5 stars.