I've been into the "Christmas horror" thing a few years now and this is about as dry and dark as you can get. Some obvious parallels to Rare Exports or Sint, but there are no children (or humor/joy) to be had here, setting a much bleaker and darker tone. Not a bad thing in itself so long as you know what you're getting into. The few other reviews are pretty much spot on. Characters are largely 2-dimensional and the movie feels bloated with so much going on. It really felt every minute its length.
Suffice to say this felt a lot like Rob Zombies Halloween, only set to Christmas. Since "Silent Night, Deadly Night," many have tried cashing in on transitioning the success of Carpenters original "Halloween" to the Christmas season. Besides "Black Christmas" most devolve into various degrees of campiness. Beyond the over the top blood spurts, this plays pretty much deadpan (although I did chuckle at the creation of a human-snowman, very dark humor granted).
In sum I largely agree with the other reviews, and despite its impressive destruction of Yuletide Joy, I must give high marks for what is, in my opinion, the most successful transmorphing of "Michael Myers" to the Christmas horror genre