I just got these yesterday and wore them in our 8 degree weather with tons of snow and ice on the ground.  I wore just thin socks in them, and my feet were toasty warm on both the drive to work and walking from the parking lot on campus.  I was pleasantly surprised how warm they were since the lining isn't super fuzzy.  I also didn't slip at all in the icy parking lot, so I felt very steady.  The only reason this isn't getting 5 stars from me is because although the foot part is extremely comfortable and fitted (i.e. you won't clomp around in these), the top part of the boot is stiff and is a little uncomfortable against the calves when sitting for a period of time.  Walking, you don't really notice, but driving you do.  I have large calves, but it's not that they don't fit around my calves but more that they are stiff and hit my calves in a weird place.  This also makes it a little odd for pants-tucking.  Dress pants are easy to tuck, but I think jeans will present a problem since they will make it all the tighter and put more pressure on the calves.

These boots are not the tallest boots I've ever had so I'll be sure not to tramp in the 12 inches of snow we have right now and stick to sidewalks and roads.  If you are in deeper snow, they snow will go inside your boots.  The folded over part does unfold to go up your leg, however that part is not waterproof.  The ribbon is easy to take on and off to change it or wash it.

All in all, great for the cold weather and a solid boot.  I would recommend this to anyone, and they may not share the issues with the top of the boot the way I do.  I bought the grey on sale for a wonderful price!

Update: 4/5/11 these boots totally loosened up in the calf so now I can even tuck some jeans down there.  Total comfort and definitely worth a 5 star rating now!  They lasted well over our scary winter, so about two months, and I wore them every day to and from work not to mention in sloppy mud as things thawed.  They squeak a little, but the comfort, warmth, and water/mud proof qualities are so worth baby squeaks!