I agree with HD, the blanket lining isn't very warm. The man made fleece is substantially warmer and is what I wear around the farm during most of the winter. When it gets much below freezing, and I'm not being active, I layer with a sweater. When the outer shell gets dirty, in the washing machine it goes. Pretty simple maintenance.
Nothing matters much and most things don't matter at all.
The faux fleece is a better insulator because it traps tiny pockets of air between you and the jacket. As I understand it, Its also one of the reasons that fleece, real or fake, can be warn in a fairly wide range of temperatures, because the air pockets help to keep you from sweating. From my experience real sheepskin maintains its loft far longer than faux, but for the price of a real sheepsking jacket, you can by enough fake ones to last a lifetime....plus faux shearling if washed and then dried on a fluff setting with a few tennis balls will fluff it right back up again. Id still choose real shearling any day of the week because I like the feel, but for something like a denim jacket that wont last forever, there is nothing wrong with faux sheepskin.