I don't really like it, but at least it's original. I got through it and was even sometimes amused, but I still think it's basically dull and I certainly didn't do anything so silly as trying to watch watch more than one episode at once.
It's about the daily work environment of demons in hell. Hozuki is the main assistant to Lord Enma (aka. Yama, Yeomna, etc. depending on where you are in East Asia), who's the Buddhist god of the dead and the one who passes judgement on the deceased. If you've been bad, he'll be choosing your torture. However this anime's Enma is also a big fluffy sweetheart, whereas Hozuki is a cold-blooded bureaucrat and professional sadist. His duties include paperwork, employee training and management, diplomatic contact with other religious realms and a bit of torture if he feels like it.
The show's problem is that Hozuki is a static protagonist, i.e. he's boring. He doesn't get stirred up about anything. He just does his job and that's it. There's a Chinese Celestial Beast in Shangri-La with whom he gets on spectacularly badly, but otherwise it's like following the adventures of a robot. He lives to work. He has no other motivation. The nearest he gets to a personal life is growing creepy goldfish flowers. He has preferences, e.g. he thinks maid outfits look attractive and he can't eat spicy food, but he never actually acts on any of those personal feelings. We just hear him mention them.
This show reminds me of the few volumes I've read of Zentsubou-sensei. They're both essentially stand-up routines rather than storytelling, with the characters being used to pass witty comment on the world. The difference is that Hozuki no Reitetsu is focused on religion, the afterlife and East Asian culture and mythology (both Japanese and Chinese). Sometimes it's clever. For example, I liked the observation that if Buddhist grave offerings have the purpose of getting the deceased into heaven faster, that means rich people are buying a better afterlife and poor people will still be suffering for the crime of being poor. If you know your mythology, you'll recognise lots of stuff. Ep.4, for instance, includes Yotsuya Kaidan (which I've enjoyed in a number of live-action movie versions), Kachi-kachi Yama (a folk tale of a rabbit and an evil tanuki) and the cat bus from Totoro.
That tanuki-hating rabbit is one of the funniest things in the show, by the way. "We all have a little darkness in our souls."
However you'd probably need to be Japanese to get all these jokes, even leaving aside the question of whether they qualify as jokes in the first place. Tomoko's Japanese, but she liked this anime even less than I did. (She only watched one episode.)
For what it's worth, I have five volumes of the Hozuki no Reitetsu manga at home. A friend of Tomoko's recommended it. It's an impressively faithful adaptation and the two versions are almost exactly the same (apart from some reshuffling), but I prefer the manga's artwork. It's basically identical, but the anime looks slicker and more fully realised. There's something subtly child-like about the manga's characters, with bigger, rounder heads compared with the rest of their bodies. Firstly, that's more distinctive. Secondly, I think it's also a little funnier. If he's an adult, there's nothing remarkable about Hozuki being a cold-blooded bureaucrat. If he's a child, I think that's more distinctive. This might be why Tomoko felt disconcerted by the anime's VERY DEEP VOICE for Hozuki.
That said, though, the anime looks wonderful and is being creative and stylistically flexible in how it portrays hell, demons and other mythological creatures. There's traditional Japanese and Chinese art, famous artists (e.g. Hokusai) and even in ep.11 an animated puppet show. It can even be eerie, e.g. the goldfish.
In Japan, this franchise is a hit. It's often on the weekly manga best-selling charts and it was the eleventh best-selling manga series of 2014. Outside Japan, though, it's less successful. No surprise there. I found it interesting in a fairly abstract way that didn't necessarily make it entertaining, although it does contain some funny characters and jokes. The female characters tend to be more fun, I think, e.g. the Stripping Hag. I also liked Peach Maki, with the contrast between her bimbo idol professional identity and the demon underneath. On the other hand, Satan and Beelzebub from Western Hell can be annoying. (Maybe a bit of gentle teasing of the West goes down well with the domestic audience?)
I wouldn't recommend this show, but it's probably worth sampling a random episode, just to see what you think. It's different, which is good. It looks cool. Besides, the central idea is amusing enough to carry one quite a long way, just on amiable curiosity.