This is a great mid-layer for active pursuits. Warm and breathable. Love the slim fit and great range of motion. I use this when xc skiing, cycling, and running in cold weather (cold for western WA). If it is not too windy, I have been able to use this down to 30 with only a lightweight base layer when active. The insulation in the chest does a good job of retaining heat so I usually have to take it off if I'm active and it's above 45 or so (I do run slightly warm though). The one downside to the breathability is that wind cuts through so it's good to pack a lightweight shell on windy/wet days. If you plan on stopping in the cold, this won't keep you very warm so definitely pack a puffy or another insulating layer. The two gripes I have are durability and fit around the neck. The fleece in the back seems durable enough but I ripped holes in the front baffles of two previous Deviators by washing them with other clothes. OR customer service was great about taking them back but this is still kind of annoying to have to wash by itself (I just don't wash it now). Also, the jacket fits well everywhere except for the neck where it is very hard to zip up past my collarbone (I don't think I have a larger than normal neck). I usually end up leaving unzipped to the bottom of the neck and probably lose a little bit of warmth because of this.