I first came across Shiki a couple of years ago actually when the same group that was scanlating Pandora Hearts said they would start scanlating Shiki as well. So I read the summary and go to the "small village with people mysteriously getting killed off" and did a "AUUGGG, HIGURASHI! *flees*" sort of deal. However I enjoyed this series way more than Higurashi and it was one of my favorite anime of 2010. A quick note however, while it's not very hard to figure out what the "mysterious phenonmenon killing off the villagers" is, I do try to write spoiler free reviews so I'll just refer to them as "monsters" and have a spoilery footnote here about that element of the show* (and try not to look at the tags).
The Good: Over the past year I've noticed that fewer and fewer movies/tv shows are scaring me and anime never does. This is the one exception to that and Shiki actually did really creep me out from time to time just the way a good horror series should, both with suspenseful cliffhangers and things-that-go-bump-in-the-night way. I ended up liking a lot more characters in this series than I expected and felt that most of them were reasonably fleshed out (although there were a few instances where a manga reader had to provide some additional details) and many of them turned out to be pretty badass in the end. And finally, this is one of only three noitaminA series to go beyond 1 cour so pacing by and large was not a problem.
The Bad: My biggest problem was how unsympathetic all the minor human characters were for at least 3/4ths of the series (and then when they did become sympathetic, well, it makes sense in context but the shift still seemed abrupt). They didn't even come off as characters but rather as flat cutouts to cause more problems for some of the characters and force the story down a particular path. What really annoyed me was how the characters were claiming that they were being "logical" when they were instead refusing to listen to anything they didn't want to hear (ie, lots of people were dieing and something is up) and this is hardly the first time I've seen this (very badly done) argument of religion versus science come up in anime in recent years (and it was presented as "oh we aren't superstitious, ie religious, anymore so we think all those deaths were a coincidence). It makes me wonder if Japan is undergoing a major mindset shift and the authors are doing a bad job of incorporating it into their works.
The Art: Yes the characters look really strange in this series, although watching House of Five Leaves almost everything looks more normal. There's no rhyme or reason for why one person has a relatively normal, abiet spiky, haircut and why another has giant pink pig tails but you get used to it after a while.
The Music: Hey, I can actually remember some of the background music! I don't remember much of the music but a remember a couple of bits played that were appropriately creepy and added well to the atmosphere. As for the openings and endings, I preferred the first opening to the second and the second ending to the first (ironically enough the first opening and second ending were by the same group, Buck Tick) but I didn't like the endings that much (probably because the second one had really weird, clip art avante garde imagery). But the first opening was pretty awesome none the less.
I may get some crap from this but I actually really liked the ending of this anime, which I know a lot of people didn't. However I noticed something, most of the people who were unhappy with the ending either really, REALLY wanted some of the characters to live/die and were pissed when that didn't happen. These were also the same people who spent about five weeks debating the morality of the monsters and the people all killing each other and frankly that got boring after about two or three weeks of debating. So if you find yourself watching this show and getting really attached/disgusted by some of the characters prepare to not like the ending. Personally I'm waiting for the two extra episodes to tie up some loose ends but I'm pretty confident that they'll work. Not sure yet if I'll check out the manga (the anime series is actually based on the manga adaptation of the original light novels which have a couple of major changes), I probably will after those episodes (since the manga has a lot of little details the anime left out) but I'll hold off until then.
*Okay, ready? SPOILER TIME: It's vampires. Ack no, don't go away, this is a really good vampire story! The original novel (written by Fuyumi Ohno, also the creator of Ghost Hunt) was written in 1998 and, since it was before the current vampire craze, the vampires (or shiki) are a lot creepier than modern day ones. They can't be in sunlight, holy objects hurt them, they have to feed at least every other night and, while they don't drink a lot of blood each time, after four eatings they kill the person, a detail that doesn't usually come up in most vampire literature.