So far I've read 26 chapters and my opinion is as follows: This seems to be a rather generic isekai, fantasy story.

The main hook of the story is the fact that the MC is reincarnated as a slime. Which is interesting for the first 10 or so chapters, but not so much after. Once the novelty of this idea is gone you are left with a middle of the road fantasy story. I mean it is entertaining while it lasts, I give it that, but it doesn't last that long. Moreover, sometimes they go a little overboard with how OP the main hero is, they don't do it often, but when they do, it is frankly ridiculous.The pace could improve a little too. I give props where it's due however, at least they didn't go for a harem, so we managed to avoid that genre trapping.

My biggest problem with the manga is the utter lack of interesting characters. The MC is as interesting as these overpowered, wish-fulfilling heroes go, fine, but I can not understand why the side characters are so bland. When I was trying to remember off the top of my head any notable side character I couldn't come up with anything. The Oni came to mind, but even in their case, I remember them more as a group rather than individuals. It's not that they are cliche, but that they are not even that, their characterization is almost non-existent. I was willing to give this a pass at the beginning because of the "I became a slime" thing was genuinely interesting, but as that started to run out of steam, it became more and more of an apparent problem.

I was strongly considering giving the manga an overall 5, due to its weak characters and lackluster plot, but since this was just the beginning of the story and it was consistently entertaining, I am willing to give it the benefit of the doubt, and a weaker 6. However, if the story doesn't give the characters some personality or pick up the pace significantly in the near future I will drop the manga.