I've read this multiple times since it was first released, starting with the web novel, moving on to the light novel and so on, also read the extremely long after stories that sadly haven't been translated officially, at least not yet. Wish they had because the after stories are great and the translation doesn't do it justice.
Went off on a tangent, suffice it to say this is one of my favorite isekai stories and it manages to balance everything quite well, with a nice harem, progressive story that doesn't stall just to drag out the time, comedy, action/drama and so on. The protagonist is very likable compared to most out there since he's not a justice touting hypocrite, no, he kills when necessary with zero regret or hesitation. That alone makes it much better than most isekai stories. He feels a bit more real (and easy to relate to) compared to the naive doormats we usually get or even the bloodthirsty chinese protagonists that overdo it and feel artificial instead.
So, why did I only give it a 7/10? Well, the manga skips a majority of the story and that's a big problem. I read through the currently released 82 chapters of the manga, which represents volume 1-6 of the LN, out of 13 total, and started to read the LN again right after and the story is just way too dumbed down in the manga compared to the original.
We miss almost every single important detail, I'd say the story is at most 1/5 of the original, probably less. We miss so many monologues, explanations to his thinking, various events happening between the scenes in the manga, the events happening to the other characters are pretty much fully excluded, hell, we even miss A LOT of the protagonist's scenes as long as the mangaka thinks it's not extremely vital, the manga simply jumps from one scene to another without fleshing it out even slightly.
There's a ton of events that never even happen in the manga at all, so we're left with a skeleton frame of a story where so many important parts are missing, of course it will look very much like a generic, dumb isekai when all the good parts are removed. It's a hollow husk, but still not a bad read.
Basically, you could read the manga to see if you kinda like the vibe, but please read the officially, fully translated light novel, It's simply far superior and to me, it deserves a 10/10, but the manga barely scrapes out a 7/10 with me being a bit generous because it's one of those nostalgic stories I keep on re-reading every few years. To me, this story will always be one of my all-time favorites, though I admit a lot of it is simply wish-fulfillment, but it's just so easy to read. I hope they turn all of the novels volumes into audiobooks and also translate all the after stories that are probably even better than the main story.