Overall it's a great jacket. Does what it is intended to do and is lighter than TNF's Free Thinker. When comparing the two Free Thinker has better seals on the zippers, but those zippers are harder to zip. The zippers for the pit zips have a very small gap between the two zippers, I doubt very much snow will ever get through but it is there. I like the offset zipper.
The cut is roomy enough for a few layers: 320 weight Ice Breaker wool base and Montbell Ex Light 900 fill down insulating layer, for those really cold days on the mountain (medium and I'm 5'7" 185, not skinny, but not fat... husky athletic type, 42-43" chest). There's probably room for another layer, but it would start to get restrictive.
The Sidewinder is lighter and easier to pack. It doesn't have as many pockets, but to be honest the Free Thinker has too many pockets.
The hood is great; fits around my noggin or around my noggin with a POC Receptor+ wonderfully.
Is it worth $600? That's debatable, but I don't regret the purchase. $400 seems a bit more reasonable considering what you're getting, a waterproof shell.