The short answer to if you should go down from your typical size or not: yes, you probably should; that is, if you only plan on wearing this shirt jacket without layering. However, if you plan on wearing this with a bulker hoodie or something similar underneath OR you have a larger stomach, then probably not. If you are interested in more specifics, please continue reading. . . I wanted a heavier shirt jacket that I could wear over a light to medium-weight hoodie for the upcoming colder months. I normally take an XL or a L depending on the brand, and if I plan on layering or not. I have an athletic build (larger shoulders and chest and smaller waist), and, usually, when I plan on layering with a hoodie, I need an XL; but being that many said this runs large, I opted for a L. Glad I did. . . The large fits well over my medium-weight hoodie, had just enough room for movement where I didn't feel like it was too tight and restricting. It also fit well enough without the hoodie, not too loose and baggy. If I would have gotten an XL as I normally would, then the fit would have been a little too loose for my liking, especially while wearing the jacket without layering. Personally, I prefer a little a snugger fit since it holds in body heat better when working in below freezing temps; but my preference for a slightly snugger fit may not be pleasurable for you. For reference, I am between 5'11" and 6 feet tall, weigh 200 lbs., have 53.5 inch shoulders, 47 inch chest and 33 inch waist (shoulders, chest and waist measured in circumference). If you are someone who likes a much looser fit and/or has a larger midsection, I would recommend getting your usual size -- at least. This shirt jacket is more streamlined in the body than what many other shirt jackets are, so if you have a larger belly and went a size down, this shirt jacket will most likely be a bit too tight for you. This I know: After I purchasing mine and wearing it a bit, I bought another one for my stepfather. Unlike me, he has smaller shoulders. . .and a fairly large midsection. He normally takes a L for his jackets, but since this shirt jacket runs a little large, I opted for a M. It didn't fit. It was OK for him in the shoulders, but the jacket wouldn't button over his larger belly. I returned it and got a large for him, which then did fit over his larger midsection, but barely. This shirt jacket does have side pockets and one pocket inside up by the chest area for a smart phone, wallet or whatever. One thing I should say about the side pockets is that they are awkwardly placed. The manufacturer put the side pockets right on the seams where the front and back parts of the shirt jacket are sewn together, and so the pockets are a bit farther back from where typical side pockets would be -- from my experience anyway. If you want to use them to warm your hands, you better have flexible shoulders. Also about the pockets. . .not the side ones, but the inside pocket up by the chest: Some people have commented that the Velcro is overly strong and thus there are some concerns of tearing the inner liner when pulling open the pocket. Yes, it is strong, like most new Velcro is, but. . .if you grab each part of the Velcro with your hands and close and open it a couple of hundred times (this may sound like a lot work, but I did so in only a couple of minutes), the Velcro will loosen up. . .and considerably. The thing that I am the most disappointed with is the snap buttons: They are very weak. The snap buttons are metal and look nice and sturdy, but several of them would not stay snapped together very well. They would pop open with minimal effort, like bending over, for example. Thankfully, though, not all of them are so exceptionally wimpy -- just a few of them. So for most part, the shirt jacket stayed partially buttoned. In all, this is a very nice looking, feeling and sturdy shirt jacket which is quite warm when worn with a hoodie. It does a good job keeping out the wind and it appears to shed some water as well. It also goes on and off very easily because of the inner nylon-lined sleeves. But because of the weakness of some of the snap buttons and the extreme side placement of the side pockets, I cannot give this more than four stars. *Update* I've been wearing this shirt jacket for approximately 18 months now, during Fall and Winter mostly, and it has held up well. It has endured a lot of abuse during that time, and it still looks good -- no tears, no scratches and no coming undone at the seams. But. . .as I stated before, those darn snap buttons sure could be a lot stronger. Many times while I was out doing something strenuous, like cutting brush or shoveling a lot of snow, I looked down and saw the bottom half of the jacket unbuttoned. I don't know if I got a bad batch of buttons, or if the rest of these shirt jackets are this way. It is a minor complaint, but it does get a little annoying when working hard and then constantly having to rebutton the jacket. And as for how warm it is during winter. . .I'm impressed. With the configuration of clothing I have shown in my photos (tee-shirt, long sleeve denim shirt, medium weight hoodie and this jacket) , I've been good in -25 to -30 temperatures (and that is not including the wind chill), that is, as long as I stay active. My face and hands were another matter, though. . . I would like to be able upgrade my rating for this jacket, for the overall quality of this shirt jacket is high and it is also very warm. But the weakness of the snap buttons prevents me from rating it better than what I originally did. **Second update** Been two and a half years of wearing this jacket. . .and it is still in excellent shape. Even though I've put this shirt jacket though a lot of abuse (cutting, hauling and piling firewood, cutting multitudes of brush and many other outside jobs where I was crawling around in the dirt), the shell is still intact -- no tears or rips or seams coming undone. The inside is fully intact as well. Unfortunately, the metal snap buttons have weakened a bit more. I recently took a photo of myself after I was done cutting down some balsam trees on my property. You can get a better look at how the jacket looks in an outside environment. And as testament to what I have been saying about the snap buttons, you can see that the lower half of the jacket is unbuttoned. It is such a shame that these buttons are so weak, for it degrades the overall quality and appeal of this otherwise outstanding jacket.
