TL;DR below for the lazy.
The first 10 or so chapters are genuinely not bad and hook you to the story, but very quickly you will realize that the illusion of depth for both the story and characters you get in those chapters quickly fade the more you read.
Story - Main character is bullied by a group of kids, said kids decide to kill his parents and nearly kill his brother. Why? Because why not. That is the reason given and frankly I don't hate it, I like the idea that characters are evil and do shit just because why not, but I also expect said characters to have depth, but more of that in the character section.
Anyway our main character Uruma decides to move in with his ex military Grandfather to train to kill these bullies for revenge. It is a simple revenge story with a good hook and setup, but falls apart from plot contrivances and inconsistencies. Characters going from point A to point B because why not. Characters doing 180s because of drama/plot e.t.c.
Overall it is a 3/10. Too contrived and all over the place, but the setup was well done and it kept me reading for as long as I did, despite everything.
Characters - The only interesting characters in the story are Uruma, his grandfather and Kyou, the leader of the bullies. Everyone else is as surface level as they can get and sadly, this is especially true for the other bullies. They are all comically evil with 0 redeeming qualities, besides one very small and short instance, you are never wondering if these characters have a reason for doing what they do and all of them have very surface level characterisation. I initially thought that all of them would have at least some interesting quirks or something else going on about them, but no, all of them are violent, murderous rapists. Yup that is pretty much it. Maybe it is because of the shounen designation and it being aimed at young boys that the author can't really dive too deep into fleshing them out as characters due to the nature of the story, but these characters would have all benefited in a seinen franchise where the author would have had a lot more freedom in how he handles them.
This is especially true for Chizuru, what would be considered the main female character that feels tacked on, because we need a female lead. Why? Because it is a shounen. At first I wasn't too mad about her, I thought she would develop and become something like a follower of Uruma similarly to Kyou and the other bullies to drive home the fact that Uruma isn't all that different from them, but no, she literally just exists for the sake of existing and that is that.
Overall, a 3/10 as well, very few good characters and the rest are cliche with no real depth.
Art - Simply put, I like it. I like how rough it is and how well it goes with the story. I like the faces the author draws for characters and the environments look decent too. Not much to complain about really. As with many ongoing manga, the art becomes cleaner the longer it goes on and the same is true here, but the overall grit and roughness is still there 70+ chapters in so I don't have too many complaints.
7/10
Enjoyment - Despite how many negative things I've said, my overall enjoyment was pretty decent as I turned my brain off and looked at this manga for what it is. edgy, gory revenge porn. And for that it is pretty decent. As long as you don't invest yourself too much in the story, it is an ok read. That said, my enjoyment has steadily been declining the more I read and frankly I don't see myself coming back to this manga any time soon. Maybe when it is finally finished I can binge it and give my complete thoughts, but as it is my enjoyment was fine, overall.
5/10
TL;DR: Has a decent premise but fumbles the bag pretty early on with a surface level cast and a story that goes all over the place. Has solid art and was fairly enjoyable once I turned off my brain and read it for what it was. Wouldn't really recommend it still, due to a lot of scenes of r + ape, like, really a lot, which I can handle but I know a lot of people can't. But the gore is enjoyable at the very least so there is that for all of the gore enjoyers. Maybe it will get better in the next 50 or so chapters, but I highly doubt it.
For anyone looking for a good revenge story, look at Oshi no ko, from the author of Kaguya Sama. It is much deeper and better realized than this manga will ever be.
