I have 5 or 6 of these shirts and love the look and fit. However, they are definitely big. Most of the other shirts I wear are L or sometimes XL if they run small. I wear an M with these shirts and can even comfortably wear a t-shirt underneath. I've had a few of these shirts for a few years and they still look great. Unlike cotton, the material does not pill and does not change when washed. The only problem is that they can be easily caught. Stay away from Velcro and other rough surfaces.