To be honest, I don't understand what this show is going for.
It was a well executed show at first. Then when the main character recieves his weapon, everything changes. The seriousness built up around the main character, the atmospheric vibe, is all destroyed by some of these "comedic" moments. As someone who enjoys Black Clover, with Asta screaming at the top of his lungs in nearly every episode, as someone whose favourite character in MHA is Bakugou, and as someone who loves One Punch Man's Speed-o'-sound Sonic, these shows just absolutely NAIL that type of character. These shows are more light hearted in nature, which makes them fit in.
The sword forger guy is just silly, and his "jokes" and the reactions to them are out of place. No attempt to give the humour any meaning or context, or make the humour fit appropriately within the calm setting the anime has set up to this point. But it gets worse. When we later on meet a doctor, her companion is also annoying. But it gets worse. When we once again encounter Zenitsu and Inosuke the show takes a turn in the worst way possible.
I understand that we are meant to feel sympathy for the demons but it's done in a poorly executed manner. They build them up as ruthless, kill them off, and then while they're dying they have a ten minute long flashback about how their traumatic childhood forced them to want to eat people in exchange for being strong. Not only does that not make sense, it actively undermines the satisfaction of killing off the villain.
Now, villains don't have to be black and white, like Hisoka from Hunter x Hunter. He is crafted as a likeable character as well as a fierce villain. They are given a personality. Zenitsus gimmick would be interesting for a demon, but for him to have it and do the same thing in every episode gets old. After the first 2 times he does it.
As for the pacing, it's really really inconsistent. In the beginning of the show it appeared though it would have a fast but steady pacing. Nope. Some fights span 5 seconds, other span 2 episodes. Sometimes we spend half an episode watching a dead demons back story, which completely removes the tension. If you wanted that backstory, introduce it when you introduce the villain not after he dies. When the "bad guy" is dead I don't want to watch his entire traumatic childhood. If these stories were told before they die, maybe I would actually feel something for them WHEN they die. That being said Tanjiros reactions to their deaths are always bittersweet and well executed.
Pacing when it comes to the "funny" bits is also wierd. 5 minutes of Zenitsu saying the same thing over and over again is NOT funny. I mean, if new things happened, if the characters said different things each time in new ways, or if there was a dialogue between them I wouldn't mind. But it's just Zenitsu monologuing the same couple of lines for 5 minutes. I skipped it every single time. Inosuke had this problem in the beginning as well but got better as the show progressed. I hoped it would do this for every character but it refuses to.
Something else it refuses for its characters are words. Yes. Often, characters do not respond when spoken to. And sometimes characters don't listen to what's being said. And it made me hate almost every demon slayer. This is how Inosuke was introduced. Hot tempered, refuses to listen, even though he talks, while Zenitsu in the same scene, refuses to talk. Tanjiro refuses to talk as well. Tanjiro later refuses to talk to the Hashira. Like, I'm sorry, but building up story moments and refusing to build an understanding between MAIN CHARACTERS but then doing it for VILLAINS is infuriating. Basically the only character you like is Tanjiro, because he's the least stupid and not evil.
...with all that being said there are certainly qualities in this anime, though it is not related to the characters or the pacing. The story is mostly good. The fights are beautiful and exhilirating. It's what I enjoyed about it, and I endured the other aspects to hopefully find new, more redeemable qualities, and it got slightly better after reaching rock bottom.
The Art is mostly beautiful... however, why do no female characters have pupils? Why don't the demons have them? How do they see? Half the characters have lifeless eyes and it doesn't help to make them feel more alive. There is an overuse of the 3D models as well. They look worse and very distinct from the drawn characters and its breaking the immersion to needlessly switch back and forth in scenes when they just .... STAND STILL! One thing to do it in fights to allow better camera movements, but when they are standing still talking.
I will watch the next season, but I want it to be better than this one. I want it to be good and I believe it can be better. A lot of talent and effort was put into this.
EDIT: Because I think I may have been unfair to the series in a variety of ways, I vow to rewatch this sooner or later. When I do, this review will get updated.