It's quite good. I'd recommend it. It's yet another zombie film like all the gazillions of others and its Christmas elements are superficial, but that doesn't make it bad.
It's set in Los Angeles, which means it looks about as cold and snowy as Hawaii. A woman (Nadine Stenovitch) is talking about dumping a man (don't know who yet), when BAM, zombies. The filmmakers didn't waste any time there. They're disgusting and they'll bite you. That's all you need, isn't it? This isn't a blockbuster film, but the production is taking itself sufficiently seriously that the zombies look real and you'll be cringing when people open doors. Before long, Stenovitch is besieged in an apartment with two cops (Jack Forcinito and Andy Hopper). One of them is probably the man she was going to dump, but we're waiting for clarification on that one. Hopper is injured and had a zombie chomping on his shoe. We'd like a bit of reassurance there too.
The film works because it has characters, not cardboard cut-outs. Jack Forcinito and Andy Hopper are best friends, but an incident the previous evening means that right now you could imagine them "accidentally" shooting each other, if given half a chance. Forcinito's a son of a bitch who seems to deliver half his dialogue while sneering. He's a good cop, but an unpleasant human being.
It works. The emotional content and caustic characterisation is strong enough not to be overwhelmed by the fact that zombies are rampaging outside. You can feel the pain in the "I'm leaving you" scene. Later, when the characters start taking risks, it doesn't feel like annoying horror-movie stupidity, but instead Forcinito being, um, himself.
The zombie stuff is mildly interesting. It's aware of the "running" vs. "non-running" divergence in zombie movies, so it has two kinds of zombies. There are slow ones and fast ones. The latter are crazy, red-eyed and get an unnecessary biological explanation. I quite liked it, but I'd have liked it a good deal more had the film done anything with it whatsoever. Anyway, the running zombies are almost cunning. They learn to duck out of sight of guns. They'll take cover and ambush you. One of them is practically superhuman. You can study their behaviour and psychology, e.g. their behaviour after dark, or the noises they make. One mews like a kitten, while another howls like a werewolf. I liked all that.
You'll need to be charitable with a couple of plot points. Everyone cottons on immediately to the "I've been bitten" rule, but perhaps they all grew up watching zombie movies too? I'm also not sure about the smell-extinguisher, but what the heck.
The Christmas stuff doesn't make much difference to anything, but there's a Zombie Santa and some light-hearted use of incidental music. Note the sychronisation of gunfire to the cymbals in a certain well-known piece, for instance.
The cast aren't particularly famous, but they're not nobodies either. The three main leads haven't done anything I'd have heard of, but they're perfectly okay and Forcinito is having a lot of fun being ugly, callous and abrasive. However there's an interesting face or two in the supporting cast. There's Vernon Wells (Wez in Mad Max 2: The Road Warrior, Bennett in Commando), Felissa Rose (Sleepaway Camp and sequels) and Lew Temple (The Devil's Rejects, the 2006 remake of The Texas Chain Saw Massacre and an ongoing role in The Walking Dead). I wasn't wild about Temple, actually, or to be more specific, his last speech.
If you're looking for a Christmas movie, you could do better. That side of things feels like a bit of an afterthought. Within the narrative, is it Christmas today or next week, for instance? However as a zombie movie, I thought it did the job and made me tense in that way that I think is peculiar to zombies. It's not cheap garbage and it doesn't wink at you. It's nasty, e.g. the cauterisation. It has gore, horror and well-done character work. I was quite impressed, actually.