Demon Slayer or Kimetsu no Yaiba, is a very decent popcorn manga.

The anime may have very good animation to cover up its subpar storytelling, fights, and character development, but reading the manga really helps highlight the fact that it is nothing very special.

The manga can be very good sometimes (some of its fights and some events in the plot) but it rarely does so, making it a trudge through the bad to get to the good part kind of manga.

If I could give it some credit, Demon Slayer's simple storytelling is very good for a shonen. What I mean by this, is that most shonens I have read, usually never do anything ambitious with their storytelling, albeit killing of a character or leaving some plot elements up to the reader to fill in themselves. Demon Slayer however does both of these things, which boosts it up a little in my opinion.