Fans have nicknamed it "'Salem's Lot: the Anime", because they're both about a local community with a vampire problem. The original author also saw the similarities and dedicated the novel to 'Salem's Lot. (She's Fuyumi Ono, whose work was also adapted into the superb Twelve Kingdoms.)
It's quite good. I liked it. It's an old-fashioned vampire story, sticking to the traditional lore (which always pleases me) and its innovations feel like reasonable extensions instead of breaking the rules. It's slow and sinister. The families who "move out" in the middle of the night, including children... brrrr. It takes a good few episodes even to reveal that this wave of deaths is being caused by vampires in the first place. Their black eyes are creepy and the whole thing's satisfyingly dark and lethal.
The Japanese setting adds an interesting twist. The mountain village is so convincingly portrayed that at first I had trouble imagining anything supernatural happening there at all. The Japanese custom of cremation might appear to be an obstacle for a vampire epidemic story (and it also inconveniences Japanese Muslims), but as it happens this story's village is one of a very small number of Japanese communities that still buries their dead. There can't be many of those, but presumably the vampires went looking for it.
The art can be odd, though. The show successfully gives unique faces and builds to everyone in a huge cast, but it achieves this by being unafraid to be cartoonish or even bizarre. Until I got used to it, this could be mildly jarring.
The moral debates are interesting, but not because I agreed with them. The second half goes to considerable trouble to build up sympathy for some of the bloodsuckers, but what they're actually saying is laughable.
"I've done nothing wrong. I just fed. I didn't choose to become a creature like this."
"I don't want to starve to death. Is that really such a sin that I must be staked?"
"Men, too, rob animals of their lives in order to eat. But, despite this, what men do is acceptable, yet what we do isn't?"
These arguments are superficially reasonable... until you remember what we'd been hearing from exactly the same vampires to explain why murder is natural and normal. They have to kill to eat. They reject the idea that there's any sin involved. Okay, fair enough. We'll run with this for argument's sake, even though they could easily have fed non-lethally since their victims don't die until they've been drunk from for four consecutive nights. (And they kill their own loved ones, including children, even though most of their victims don't rise again but instead stay dead.)
But, by exactly the same argument, humans have the right to kill in order not to be eaten. Dragging sin and "acceptable" into the discussion is pure sophistry, since the vampires had denied the relevance of such concepts when they'd had the upper hand. (Yes, the humans go kill-happy when at last striking back, but that doesn't invalidate the principle that eliminating vampires is a good thing.)
There's plenty of interesting material here, though. There are grey areas and atypical individuals on both sides. The most hateful person in this series might be a 100% human mother-in-law in episode 21.5, but Natsuno's father and the whining Masao are also in the running for that title. The doctor's actions in ep.13... bloody hell. At one point, I lost patience with the smug idiot villagers who'd repeatedly refused to listen to the "unscientific" truth, but soon afterwards I was in awe at our heroes' way of proving their doubters wrong.
This is a dark, bleak series, which for some viewers tipped over into "too bleak, stopped caring". It's exploring the horrible side of human nature. It can be shocking. Megumi's death, yow. (Well, both of her deaths, really, but I'm thinking of the one involving tractors.) Terrible things will happen to good people, while bad people might get clean away with it and/or even be seen as heroes. Our heroes can be stupid, although sometimes also ingenious and clever. This one's pretty good.