The movie is just so joyless and uninteresting most of the time. The pacing doesn't work at all IMO and the two plots seem complete at odds with one another.

In Violent Night, we believe the character is Santa Claus. In Fatman, he just comes off as some random guy who can't pay his bills and runs a factory. For me, Fatman needed a better introduction to the world and Santa to buy into the rest.