Phenomenal, and worth the cash.
I'm new to the whole frigid winter experience and subsequently did a lot of research prior to investing the necessary amount of cash into wool products...initially I tried out 3 different brands, but it took very little to become addicted, and ultimately I've become an Icebreaker girl. The wool is good quality, doesn't itch, doesn't hold odor, and the clothing just generally looks nice.
I've now own two of these tops, and they're amazing! I pretty much live in them. They wool is thin that's perfect for layering; there's even got room to wear another light shirt underneath for when I have to spend a lengthy period of time inside a warm building. And the stitched in thumb holes are a must!
They run just about true to size, perhaps a hair large, but it allows a little room for those with more of an hourglass figure.