I have yet to try these on a really cold day. However, I have used them a few times and I can tell they definitely help.

One small complaint that I have is that they do seem to add a little bit of bulk, which I wasn't preparing for. Also, they don't cling as tightly to my body as I'd like them to. I guess I was thinking these would be more of a compression like material as opposed to what they are. They seem to bunch up a bit near the back of my knees and they go above my pant line so that I roll them down or tuck a shirt in over them so that you can't see that I'm wearing them.

All in all, I'm not disappointed. I'll definitely be using these at work. I'm always going outside in the freezing cold, rain, snow or just below freezing. Next pair I buy will be more of a compression like material though. I would want them more snug.