(Spoiler Free) Read if you are unsure whether or not you want to watch Shiki to see if it's for you.
Shiki is one of the most beautifully depressing anime I have ever seen. It is incredibly dark and tragic. I made my account here on Anime Planet for the sole purpose of writing this review. It has not even been an hour since I finished binging it, but I felt it was neccessary to write something given its bad rep.
Scare Factor / Gore
This is not a jumpscare type of anime. I don't think there is a single scene that is directly created to incite instant fear in the viewer. The scariness of this series is more deep and drawn out. The buildup, concepts, and the dark scenes are what truly lets Shiki imbue the viewer with fear. Fear for specific characters or how a scene will play out. You never really know if someone will be alive or not by the end of the episode. It is written in a way that creates a sense of dread down to your core. From the way some characters act to specific gruesome scenes, this series is best watched at night with the curtains closed. As for gore, this isn't a series for people who have trouble stomaching death. From decaying bodies to brutal murders, there are some select scenes that will undoubtedly make your skin crawl. Gore has always been a big deciding factor in whether or not I would watch an anime, so if you don't feel up to it, put this aside for a few years and try again later.
Shiki is a dark series. After you finish this series, you will be left with a complete sense of dread. So why do I see it as such a beautiful thing? Two reasons: Realism and philosophy. This series is riddled with it. Many of those who hate this series find the characters revolting in how they act. They hold the expectations that characters will always do extremely rational things, but they fail to understand one key factor that makes this anime different from others. People, in general, don't do rational things. Especially in a life threatening situation or a tragic event, people don't normally keep their cool. They act before they think. This is one of the reasons I rated the characters a 10/10 for this anime.
The other issue you may have trouble with is that this series is 24 episodes long. It has a long buildup to the climax, and starts out slow. I can't beat around the bush with that one. So why is it so slow? Character building. Everything shown in this anime has a purpose. The first few episodes are still exciting in their own right, but are slower. These episodes are for world building and character introductions. This series does an excellent job with the pace at which characters develop. The viewer can watch as a character slowly sinks into every level of insanity. Even better, the viewer knows exactly why the character feels this way and has a near complete understanding of their situation. You can really connect with the characters in this way. And in the same right, it makes the series just that much more tragic. If you choose to watch Shiki, you will likely find yourself confused on which character/side you should be rooting for. You might as well just feel sympathy for everyone involved.
The message behind the story of Shiki is very neutral and not set in stone. The story is heavily based on the concept of there being no good or evil in the world. The philospophies that this series stoops in are dark and almost nihilistic. If you are the type of person who likes to finish a story and know exactly what the meaning is behind it, you may have trouble with this series. But the wonderful part about how Shiki goes about its own open meaning is that it is very easy to understand it in your own way. It isn't void of meaning, but rather is open to interpretation, quite like a piece of artwork. As someone who greatly enjoys the use of philosophy in anime, this series will be unforgettable.
The animation isn't anything to gawk at. It isn't increadibly detailed like some, but it certainly isn't anywhere near being bad. Character's faces can heavily vary based on their personality/age. The way that hair is depicted in this series is especially unique with its jagged, floating style. The most important aspect about the animation is that it works incredibly well with the story. It is a dark, more gloomy series, and I belive the animation compliments it splendidly.
One thing people pretty much unanimously agree on is that the soundtrack is awesome. It is one of the most important contributing features in building the enviornment and feeling behind each scene. The music in this series works incredibly well in immersing the viewer into the story.
There isn't much more to say. If you stuck with me and read through what I wrote up to this point, it's obvious you're at least somewhat interested in the series. Personally, it was worth my time, and maybe it will be worth yours too. Give it a shot!