It might just be the color option I got, but it is somewhat translucent, so I wouldn't wear this by itself if you're uncomfortable with having any part of your torso visible to any degree. Thankfully, it's lightweight and very breathable, so it's no problem wearing this over an undershirt or shirt. It stretches very well so it doesn't feel tight anywhere, even when wearing something under it. My one problem is something that all clothes typically have for someone that's 6'3", and that is that I buy in a size that mostly fits, but the sleeves end up being shorter than I'd like. But since that seems to be a universal problem at this height I'm not docking a point. And again, it stretches very nicely, so I feel like it's more forgiving than other shirts I buy at this size.
I wore it during a hot day recently (around 33C/90F) and I can definitively say that I did not overheat in this despite it being long-sleeved. And I definitely did not feel like I was burning up as much I typically do in short sleeves (UV index 6/7). So overall I'd say it checks all the boxes. It protects, it's comfortable, you can wear it in pretty much any weather, and it cleans up nicely. Another win for Coalatree!