Most episodes are more-or-less standalone, so it's not really a "must-watch-next-episode" series, but more or less every episode is great by itself.
Can't really say it is a masterpiece, as I usually want a more overlaping story to get really engaged, but every short story fits the mood, so if you like classical horror you will propably enjoy it.
Also worth to mention that the animation is great.
I just finished watching this series recently. Actually, I downloaded and started watching the series a few months ago, but it took me a while to get around to finishing it.
I didn't care much for the show. The last couple of episodes are pretty good, but overall, the show is below average.
The animation is good, and there is a lot of cool gory things that you expect to see in a horror series, but there are a lot of problems. One, each episode is a stand-alone story, which is good, but there is a main cast that the show focuses on, so each episode is sort of the same. You have the author doing something at the beginning of the episode, some weird shit goes down, and the three "spirit people" wrap things up at the end. For the entire series.
The biggest problem, is my opinion, is that character designs are wird as hell. That may not sound like a real problem, but let me explain it like this: You start watching the show, and everyone looks normal (well, normal for anime); then, you'll see a person who's essentially a frog person, 2 feet tall with green skin, and you don't know if this frog guy is a normal human or something special; well, everyone acts like this person is completely normal, so apparently, being a frog person is okay, except that no one else in the show looks like that. That shit happens all throughout the series - "Hey, that person has a stick for a head. Does that mean he's evil? No, he's just a regular guy. Huh."
It may not bug other people, but I thought it was horrible. And not just aesthetically. I think it was a bad thing to do because horror shows either take place in our world, and the weird things happening are supernatural, or they take place in a fantasy world, and what's unnatural to us may be normal to them. This show seemed to try to mix the two, and it doesn't work. The viewer ends up confused, and things that should have meaning, don't.
I guess I should make myself more clear when praising something. This show is great, not the greatest but it certainly is better than most.
I recommend you to watch the first episode and see for yourself, just as ShaggyJebus mentioned, the episodes follow a similar pattern and deals with things you can expect shorter horror novels to be about.
If you like what you see, you will pretty much like the whole serie.
Also, this is great gore, not just some gore thrown in because a horror story needs it, or because it is cool. This gore is pretty much a work of art and fits the aesthetic of the serie perfectly. Just as the absurd stickhead fits, that is art for you.