Purchased these 2 months ago, and now that they are finally weather/nature tested, I am ready to write the review.
I have been wearing them for vigorous winter nature walks here in Upstate New York. They are warm but not overwhelmingly so. Once broken in, they are quite comfortable and don't feel stiff. I have covered a lot of mileage in them in the snow and slush, and in very mixed terrain (including bushwhacking on some mountainous terrain).
YES, THEY ARE WATERPROOF! I missed the shore of a small pond and went in through the ice - the boots were submerged for a few minutes almost up to the top rim, but my feet remained warm and dry in the ensuing scramble. I have waded through some mud and puddles and they haven't failed me. Highly recommend / would purchase again.

Oh, and even though I have been wearing them a lot they still look like new