Why wear it? Because it's freezing goddamn cold outside.
What does it do? With the exception of a brief, strident burst of lavender early on, Black Mark muffles you up to the chin for hours in a friendly fever of fiery cedar and mellow saffron. Better than a sweater!
How do I feel? At least five degrees warmer. It doesn't seem like much, but in weather like this, it makes all the difference.