In my first try-on....they are light-weight but feel substantial enough to protect me from the cold (along with a Columbia snow coat, which was wonderful, too!).  I wear a size 8 normally & I ordered a size 8 - they feel pretty snug with regular socks on.  The purpose in the purchase is for a vacation to New York from my home of Texas...so I am not used to the cold.  They do feel cozy!
I really wanted some vegan boots, but I couldn't find any that were water-resistant, breathable & warm.  My others cause my feet to sweat, which does not ensure warmth!
Now I will have to wear them in Texas 60 degree weather to wear them in a bit before my trip!

*To follow up after months of wearing these boots:  I love them!  I wore them all day long while walking the streets (wet & icy) of New York and they were completely comfortable, dry and warm inside.  We even got a few days of snow in Texas, so I got to wear them on walks in the woods.  I love them, great buy!