I've been using it and it seems to be helping. My neighbor scoffed at me and since she has an insulated coop (mine isn't) she didn't feel the need to use it. This morning when I went out to help with goats, she said "Oh, Sam's OK." ?? "He got frostbite so bad last night that his comb and one wattle split and the hens have it too though not as bad."
My hens actually are starting to look forward to it since the vaseline is warm and they get to spend a minute getting cuddled and rubbed.
Yes, the heads will be goopy and turn black from dust (scared DH, he thought it was all frostbite, but I had to show him that it was dirt and could be rubbed off) but between closing the pop door and lubing the chickens up during the day (in the teens here with an even colder windchill), mine are doing fine.