I was surprised at first at how warm these boots are- the liner is amazing!!  My only concern is, is that they really don't tighten very well, so it feels like the boot is always slipping.  I will primarly use these for snowshoeing, but haven't had them out yet.  I wore them while snowmobiling in 20 degree weather, and warmth was never an issue.  I also wear them for work, and they work great!