I tried on a large in the store and felt like I was swimming in the lower portion/stomach area of the jacket, but I really wanted one since they were on a great sale. I ordered a medium online hoping the sizing would work out. The medium did fit better in the mid section, and borderline too tight in the shoulders; but unfortunately the sleeves were just way too tight to deal with. I could barely put the jacket on over a wool base layer due to how tight the forearms were. Taking it off was equally as hard. The sleeves in the large were also tight fitting, but I only had a T-shirt on when I tried it on in the store.It was very comfortable feeling, and the hood/collar was the same cut as the micro therm 2.0 down coat, so layering those pieces together would have worked great. I can't speak for the warmth or windproof of this jacket since I only wore it indoors before deciding it needed returned.