What it is, is a high quality, lightweight insulating layer that's suitable for knocking around in, or taking up a small area in a pack for when it's needed. And when that time comes, it does the job nicely. Size med. fits my 5'-11"/145lb body just right that I can get a Polartec 300 fleece layer under. Someone else my size would probably be able to make do with a small, but I wanted something to throw on after a day of hiking/skiing to a campsite. The collar doesn't cut off oxygen, nor let in cold air. Nice inside pockets suitable for bottle(s) and Cliff Bars from freezing aren't usually mentioned, but there's one on each side. It's a great value considering the price & the quality of construction & materials. I wouldn't hesitate to depend on it at -10F with a decent shell and some R1 fleece underneath.
For a lightweight insulating layer, at even $50-$75 more, that'd be a keeper.