I wear this every morning on my morning commute, 28 miles to work.  The coldest ride was about 12 degrees F.  It keeps everything it covers MUCH warmer than bare skin, thats for sure.  At extreme temps your skin will still feel cool (at least with 70MPH winds, like on a motorcycle) but it won't get cold or numb.  Now your exposed eyes and bridge of your nose will hurt a lot...

If you ride in the winter, get one of these ASAP.