Imagine working on your manga idea for four years and this is what you come up with.
Android samurai hackers in space with epic gamer shut-in as a protagonist. No, this isn't a B movie idea, this is the basic plot of Samurai 8.
From start, this manga feels like the reader is missing a chunk of information, like it's a sequel or a spin-off set in a world we should already be familiar with. The story is chaotic, confusing, all over the place and doesn't really bother explaining itself much. Which is quite ironic, considering 75% of the manga is infodumping. This isn't an overstatement.
Awful plot devices are used to set things in motion and the power system is not explained beyond "reality is whatever you believe it is, yo", leaving all of the fights without any tension, as it's obvious from the writing style since the start that the protagonist will just bullshit themselves into victory every time, no matter how weak they start. Well, that and the fact that they can regenerate from almost everything. He gets literally sliced up during a training sequence and pulls himself back together like no big deal. Because that is the way of samurai, duh.
The manga is full of pseudo-deep quotes whose only job is to sound cool, intellectual and make it look like it's some complicated, well-thought dialogue. It isn't. It is even remarked by the main character few times that the explanations are needlessly confusing, though I doubt it's a meta humor directed at the manga itself.
The characters are your basic uninteresting shounen cast, most of them not being flashed out at all and just kind of existing there. The protagonist it your typical "my kokoro and spirit will make things work" and of course it's quickly discovered that while weak at the start, they actually had fox demon, wait, no, a samurai soul inside of them the whole time that makes them incredibly powerful. It also includes my pet peeve which is including a blind characters only for them to act like they have normal vision most of the time while the manga reminds you they are blind from time to time. Is there any reason for them to be blind at all beyond "look how amazingly they can find even though they are blind, so cool!"? No.
The romance of the main characters (if it even can be called such) is laughable and arranged marriage-tier. While their relationship might be explained by destiny, it is actually disguise for author's inability to write a believable romance. They just kinda like each other because uuh reasons.
The art is hard to read, especially in the first half of the manga. It's often hard to tell who's where and what is going on in the action scenes. Overall it looks like a spin-offish Naruto fancomic (I've actually tested this by sending pages of this to people who haven't read Samurai 8 and they thought it's either Naruto or Boruto). I have no idea why Kishimoto chose to just write the plot and leave all of the art to his assistant that never made his own manga before. At least hire someone competent if you can't be bothered to draw your own art. The space setting is wasted and it would make no difference if all of this happened on the same planet. Actually, it feels exactly like that - there is very little originality and variety.
But to say at least something positive, I expected the final chapter to be much worse, since the manga got axed. Yes, it was still unbelievable asspull bullshit, but taking the publishing situation into account, it was an okay way how to end this manga, albeit very rushed. But I feel we would get very similar finale even if Samurai 8 would go on for few hundred chapters more, so at least we don't have to waste more time on this series.
With Kishimoto's second manga serialization being an absolute trainwreck and his one-shots being not really great, I'm almost convinced that the success of Naruto was just a lucky fluke. I also believe that anyone who claims that this manga is "actually good" and "they kinda liked it" just refuses to believe that Kishimoto could have written something this bad.