Reverend insanity is a unique novel and unlike most xian xia novel, it features a "evil" protagonist, fang yuan. 

It is a story very different from other cliche xian xia that are full of saving jade beautes, unphelding justice (hypocrisy), full of "smart" but actually very dumb characters, and finally full of pulling out new realms from their a*s...uh right did I mention the stuff about young masters....I think everyone know about those 

Anyway it is a novel similar but completely different from them, it has all those elements (except author pulling out new realms from their a*s) but with a few level upgrades 

For example, there is young masters in the story...and they are very arrogant... completely normal, right? But the difference with reverend insanity is that the young masters aren't just that, they have a personality of themselves and are actually smart and can actually think...their mindset are flexible too..you know not those one dimensional idiot young master in normal cultivation novels 

in the world of reverend insanity, idiots can't survive, thus those who are have aged more and are stronger naturally have sharper minds and are more intelligent, specially the main character fang yuan who have lived for five hundred years and traveled back in time (spoiler, he can't solo everyone with that alone) 

Now, let's talk about the cultivation method in reverend insanity, the cultivation method in here is quite unique and unlike other stories where, there is hundred of different techniques and scripture, reverend insanity introduce us the concept of gu. 

Where's cultivator to even be able to do anything and be different from normal people must acquire gu, adorable and formidable creatures that, more powerful they are rarer they became and more changeling it is to obtain them and to add to the complexity, every gu has their special dietatry needs to survive–some needs normal dirt, some need eating blood and even human organs and some needs heavenly treasures that are very hard to find– and gu masters (the equivalent of cultivators in reverend insanity) need to take care of their gu worm and feed them. 

And now the "pros and cons" of the story 

Starting with bad side of the story, it would be 

1- overly detailed environment and over describing them: this is a serious problem that RI have, author likes to describe the environment and tell us about many useless ditails, for example, it is day or nigh, is there birds flying in the sky, is there any moisture is the air, describing bit by bit even every cracks in a buildings, etc. although this problem is mostly for volume one and it will became significantly better after that, but still, many new readers can't go through them. 

2- the same as the previous problem with the fights: fights in reverend insanity are clever, like it is mostly about planing and how to use what you have, but for many (specially in the early part of the story) it can be a serious problem.

.....so now let's start with the good stuff about the story, huh? Why I said only two negative thing about the story? Because first I'm biased (obviously I'm giving this story five star, obviously I'm a cultist that worship RI) and two many things that are problems for people I actually enjoy so...yeah 

Anyway, back to what we were doing 

1-story is full of philosophical elements: I don't think there is a need to explain this...you would find out anyway 

2- characters: as I said before the characters in RI are not just npcs, they have actuall personality, thoughts, goals, a story, and best of all they can think, they mostly act after thinking and comparing the gains and losses. In my opinion "characters" is the the best thing about reverend insanity. Although you won't feel that much in the first volume in comparison to other volumes that come after it (even though it is the first volume character still feel intelligent and experienced, but they still can't compare with other volumes in my opinion)

3- world building: I don't think this one needs explanation either 

4- poems: author loves to put Chinese poem here and there, when important things happen, when someone wants to describe their life in their last moments, when someone wants to say about their path of life (peak character moments) or just when someone wants to describe a beautiful scene. I personally like this a lot about this story because I enjoy it (mostly because author knows when to use those poems) 

4- gray morals: righteous isn't absolutely righteous and demonic isn't absolutely demonic, there is no absolute whiteness or absolute blackness, this world is only gray with demons that wear beautiful masks and fanciful clothes and Angels who have scary horns, hideous faces and sharp and monsteruos claws. In this world even the most pure saint can massacre people for greater good and the most vicious devil can help people in need.

Anyway that was all that came to my mind 

As I said before, RI is about fang yuan, a "evil" mc, although what is evil or not is subjective, but fang yuan do many things that I'm sure everyone can confidently say that is evil. For example killing children, oh I mean feeding animals some high quality food or slavery uh I I mean giving jobless and homeless people a new home and a new job....and massacre....from when killing bugs is bad? Whatever 

As you see fang yuan is evil and although I love fang yuan's character myself, I can't deny that he do many evil deeds (in the first place author's reason for writing this novel was because, he was tired of idiot "villains" that are everywhere and wanted to write about a real demon, that stops at nothing to achieve his goals) 

Fang Yuan isn't one of those "evil" and very "ruthless" character, that are evil just because the author said and uhm because they kill people..uh so much "evil", so "vicious" I'm scared mommy 

And fang yuan doesn't just do evil for nothing and he doesn't feel joy from it... just pure benefits and gains (you know, doing whatever is easier and give the most benefits) 

At the end must say, fang yuan is a deep character and he talks about many philosophical things, but his internal monologue in first volume feels a little like rambling of a edgy teen...why I say feel? You know why if you read

So the lesson we get from all this is that read more than one volume because at the time of writing volume one (end at chapter 199) author didn't plan the whole novel and his writing style was rather..not mature enough? Something like that (must say author is the type that plan everything so not planning everything at the time of volume one...I think you can get what I mean) 

Enjoying RI depends on your own taste, but if you don't hate evil mc, I recommend you give this a try (I don't think my shallow review alone can tell everything about this masterpiece) 

Oh right, forgot to tell, there is no not planned and just pulling out of a*s encounter in RI (mostly least for the main character) 

And did I tell you fang yuan have negative plot armor? He is not lucky at all, bro know everything, plan everything meticulously but at the end for some reason nothing go as he planned (I guess that another good thing about the novel) 

Uh and I forgot to add, fang yuan don't get any character growth on his journey (though his horizons get broader) because he is 500 years old, what more character growth can someone wants? Anyway, although there is not much character growth for the mc (there is plenty for other characters, thus why I said "characters" is one of the best things about this novel) but seeing fang yuan's past itself is better than any character growth, from who was fang yuan and how he became like this, the contract of past and present, the dynamic between them, it is just beautiful