I know Brenda Valentine gives it good reviews. I get cold easily too, but I haven’t used it because of the bulk of carrying it around, plus I wouldn’t feel safe on stand while standing up and especially turning around to shoot the other side or behind the tree. I want to feel something solid under my feet - the platform, not a sleeping bag.
What I do to keep warm is use those handwarmer heater things above my toes in between a layer of wool socks, plus in my gloves and a big one in a hand warmer that goes around my waist for if my hands still get cold. Make sure my neck and most of my face is covered, two layers of long underwear plus pants, several hoodies and coat topped off with coveralls if necessary underneath my scentblocker gear. How many layers depends on how cold it is, obviously. I kind of end up looking like the Michelin Man sometimes (remember the doe pic,) but its toasty. This year I think I might try those therapeutic pain relief heat thingys that you stick on your skin. The commercial said they last up to 8 hours. On those really really cold days I bet they would feel good on the back of your neck and lower back.