Rating: 4 / 5
I recently just ditch wearing Smartwool Micro weight boxer-briefs for these from Icebreaker. I am an immediate convert.
1) MUCH more durable. Smartwool developed wear holes soon after use. See: http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/8213/index.html
2) considerably softer to the skin.
3) no strange fly design like that of the Smartwool design.
1) Thicker and therefore warmer. If you "run hot", these will have a noticeable effect.