I wear this long underwear all winter. It are amazingly warm. I ended up buying the bottom as well. The great thing about smartwool is that it does not hold oder at all. I can wear it over and over with little to no smell retained in the fabric. When I wear these out I will surely buy another pair.
I remember a lot of the old itchy wool long johns from childhood. This stuff is a lot more comfortable (and with the merino blend, not itchy at all).This is not the first pair of smartwool long johns that I've bought. I've got three pairs now, and the build quality is very good and seems to keep for years and years.