After using LaCrosse Grange uninsulated boots for several years, I decided to try the Burly boots insulated with 1200 grams of thinsulate for tree-stand hunts on very cold days. I like being as scent-free as possible, and rubber boots hold a lot less scent than leather boots.
I tested them out extensively in the 2001 Fall/Winter deer season and found them to be very warm, which was why I bought them. My only other pair of "warm" boots is an older pair of leather off-brand boots with 400 grams of Thinsulate, and the Burly's proved to be considerably warmer. I was very pleased with the warmth that the Burly 1200 boots provided. They performed as expected in that regard.
The Burly 1200 boots are not good for walking long distances, though. They are pretty big and bulky, and although the Ankle-Fit system makes them fit very comfortably around your feet and ankles, the weight and bulkiness of the boots kind of gets to you after walking a long distance or on steep terrain. I would highly recommend them for treestand hunting in cold weather, but for stalking I would recommend a boot with less insulation and less bulkiness.
The Burly 1200 boots are available in a Camo version also.
Waterproof, scent-free, tough, warm
Fairly bulky, heavy for lots of walking