CONTAINS SPOILERS AND STUPID UGLY PEOPLE
I keep getting this movie confused with the other, earlier Christmas slasher/horror movie Silent Night Bloody Night, and indeed had to look it up on the IMDb to ensure that I was using the right title. It's not like I can differentiate between them on the grounds than Bloody Night was terrible, because this one, finally released in the UK after a quarter of a century, is terrible as well.
Both movies are dull, cheap and uninteresting, but while Bloody Night is just mainly dull, Silent Night, Deadly Night is terrible in a stupid, nonsensical kind of a way. A kid sees his parents murdered by a drunken Santa (just after his grandfather had explained to him that Santa was in the punishment racket); he grows up in a Catholic orphanage terrorised by the usual abusive Mother Superior and eventually leaves the orphanage to work at a local store. Where, come Christmas, they make him dress up as Santa. Inevitably, after way too much setup, he goes on a rampage of punishment....
Somewhat controversial in the US back in 1984: it suffered from walkouts, complaints, outrage, pickets, bad reviews, and TriStar dropped it from distribution fairly quickly. Many people were actually more concerned by the TV ads which didn't make it clear that the axe murderer wasn't really Santa Claus, particularly to the children watching. But ultimately, there's nothing of any great appeal to the film beyond some perfunctory death scenes, the highlight - if that's the word - being a topless Linnea Quigley being impaled on a stag's head on the wall. The plot is all so deperately contrived and engineered to put a traumatised Santaphobe (maybe they should have called the movie Claustrophobia) in a Santa suit and surround him with frankly unattractive people who do stupid things so that this Santa will deem them worthy of violent punishment. Meanwhile, the police are out in force with orders to shoot Father Christmas if necessary. Which, hilariously, they do. Although the funniest moment is when Mad Santa meets a little girl who insists she's been good so he gives her a Stanley knife for Christmas.
In all truth, either of the Black Christmas movies are more twisted and entertaining Yuletide horror offerings: this is slow, cheap, sleazy, and it's not enjoyable even on the cheapo 80s grindhouse slasher level. Inevitably, there's a sequel, which the BBFC threw out in 1987 and, on the basis of this original, I'm not massively thrilled about.