This is by far my favorite insulating layer I've ever used. It provides warmth when your static, and the side panels allow heat to dump when the weather is below freezing and you need to move. Since owning this jacket, I've worn other comparable items from other companies, and I get sweaty and muggy in them. I keep returning to this piece, as I don't have to constantly adjust the zipper to dump heat. Even though I knock it for not having the best weather protection, it should be noted that this isn't what this is for. The side panels allow wind to cut right through, so if it's a windy, cold morning for a summit bid, it's best to throw on some sort of shell. It also isn't the toughest material for the shell, and I have had a few gashes on it from bushwhacking. I've just thrown on a few Gear Aid patches and it is just fine. It has held up well to alpine ascents on rough granite, however, and does a decent job of repelling light rain. Overall, this has been my favorite mid layer I've ever worn. I hope it comes back, as the new Refuge is a bit heavy for my liking.