To put it simply: you will enjoy Demon slayer if you're only looking for pretty art, good animation and great fight scenes. If you want a good story and characters you shouldn't watch this.
After seeing how hyped up the show got I had to watch it. Do I feel like my time watching it was wasted? No. But I also feel like I could've spent it watching something a lot better.
I won't talk about the art and animation because I think it's pretty clear both are fantastic. I am going to criticize everything I had a problem with:
1. Characters
The shows biggest flaw are it's characters. The character designs are great but that's where the good things end. They are simply flat,boring and could be described with a word or two. Tanjiro has to be one of the worst protagonists I've ever seen. He is literally too perfect. He is cares deeply for his family, he's intelligent, has empathy for everyone(even murderous demons), he's hardworking,etc. The problem is that he doesn't posses a single flaw. When it comes to other characters they aren't any better. Zenitsu is annoying and his screaming and constant crying are supposed to be funny but only a small child could possibly laugh at his antics. I refuse to acknowledge Nezuko as a character at all because she has no personality and is only there to be cute and to save Tanjiro whenever it's convenient for the plot. Inosuke is probably my favorite out of the main four. He isn't great but I found him at least a little bit entertaining compared to the others. When it comes to the main villain of the story, he is very basic. The whole show is treating it's characters like black and white. (in the sense that a character is either purely good or purely bad). The characters either have flaws or positive traits, having both simply isn't allowed. The other characters in the show, besides their visual design, are really forgettable.
2.Story
It's pretty basic and honestly that isn't a problem. I, and I'm sure a lot of people, can get down with a basic story. A lot of times it feels nostalgic watching a show with a familiar type of plot. However, because Demon slayer lacks in characters there is nothing to carry the plot well.
3.Humor
I don't even know if it can even be called that. The jokes are,again,something a child would laugh at. If a show has a 17+ label on it, it shouldn't be there only because of blood/gore/explicit content,it should also be there because you're assuming adults will watch this. So why aren't you treating your audience like adults? Both the characters personalities and humor is something that could easily be put in a children's show and that's a problem.
4.World building
Non existent. At the start of the show you probably believed that this anime took place in an era/world where currently there aren't any/many big advancements in terms of transport or modern devices. However this isn't true because there are literal big cities,trains,etc. shown later on. The problem is that we never got a proper sense of what time period this was supposed to be going on. Another problem is that somehow people who live in cities and the police are unaware of the existence of demons or refuse to acknowledge them. I don't know who thought that that sort of explanation makes any sense, because it doesn't. We know that there are demons who live in cities and honestly since demons represent such a huge threat in this world you can't possibly make me believe that none of those city folk know about them and that the police just blatantly ignores them. It's honestly ridiculous and it's a poor excuse for the reason demons weren't destroyed by now(or the majority of them).
I think that should be all. Aside from these 4 main points there are other things I have issues with such as the existence of a lot of smaller inconsistencies or plot conveniences but I won't get into them due to spoilers. In the end, if you find enjoyment in this show that's great, I found some enjoyment in it as well. However I had to acknowledge all of my issues with it. That's all.
