Runs small. I'm 5'8", 180 pounds and have an athletic build. I wear large shirts in all sizes, but this one fits a smaller average size. I don't know how "thick" people were expecting the material for this shirt, but I think the fabric is spot on (I wouldn't plan on wearing it without a coat or anything in 50 degree weather) and the pattern looks really good I personally will buy it again in a larger size so I can actually wear it