I want to first say that the quality and feel of fabric is excellent...this would get 4 or 5 stars if its sizing was accurate.  Ive bought similar shirts in the large size from Armani, Calvin Klein, and others and none of them have the sizing issue of this shirt.  The best way to describe the fit would be to label it as a slim fit large or normal medium.  Ive got mediums of similar style from before i bulked up and it fits the same as they do.  I recommend buying 1 size bigger than you ordinarily wear.