I do not have any personal experience with it, so the following is just my opinion...
I don't believe it's much better than what's already out there... especially at the elevated prices. Silk, poly-wool combinations, polypropylene, poly-products, Thermastat and the likes are all proven moisture wicking clothes that work. I believe if you wear any decent moisture-wicking clothing next to your skin, it will help you keep that much warmer due to it NOT collecting the sweat/moisture from your body. Water cools 20x faster than air, so keeping your base layers dry is very important in keeping warm.
Also, I do not like how UA hugs your body tight. I don't like the feel of snug clothing. I also think if your clothes are a little loose, it will help trap warm air.
I'm in N. Minnesota and have experienced some incredibly cold winters and polypropylene has served my well. I also try to get one size larger and in Tall because they shrink and the extra length gives me something to tuck in.
Now if someone were to foot the bill, I'd give UA a try and give yah my experience on that. LOL!
Good hunting.
iSnipe