The artstyle is actually unique, but the writers really need to rethink the plot through. It felt like I was reading a Wattpad made by a young girl who made herself as the main character and centralized herself.

Yui is a literal doormat; she can the VERY LEAST try but nah... It's as if she had to walk through a hallway full of nails and glass scattered on the floor, and instead of using the safety boots that is beside her, she decided "oh man, there is nothing I can do." and walk through the hall with only her bare foot, leaving the safety boots (might I add, left her brain too.)

The artstyle had potential, it's what pulled me to start watching it. It gave out such a gothic vibe that promises a story like dark romance, but the storyline repeats and stays the same...

They said, "Don't blink or you will miss the plot." Honey with how little the plot is and how repetitive the storyline goes, blinking once would be enough for me to miss an actual plot throughout 12 episodes. The plot twists in this story comes out of nowhere and go nowhere.

Yui arrived, they bit her, she ran, they caught her and repeat. I thought they would at least butter up to her, but it just repeats. The writers seem to enjoy the abuse on MC lol, they romanticize toxic relationship... The abuse literally ain't criticized in the story but it is rather treated like a foreplay here. The story is not just toxic but it's so aggressively unapologetically toxic like it wants you to romanticize abuse.

I mean I do not give 2 flying ducks if people like BDSM and stuff because like... You do you with your kink babe but this story... uhh yeah if you like this shit then I guess kind answer: Everyone have their own taste, but you go girl. Not so kind answer: Are you perhaps... still young lol (or a wannabe 'cute-horror core' teen or just a weird adult.) ~~Honest answer: Ok cheap hoe, we get it, you wanna be passed around like an object. You think with your reproductive organs instead of your brain or heart.~~

The boys never change; that's the plot. 12 whole ass episodes of the same shit over and over and over again. I don't even think you can even call this story with a plot. I mean we get it, they all have their own trauma, but it's written like: "My mom died, and I got abused, so now I treat women like furniture and refuse therapy."

The boys are no different than the plot, they are the same flavored cake with different type of layout. You want options? Oh yes certainly sir, we have the tsundere sadist, the emo sadist, the lazy sadist, the nerdy sadist, the perverted sadist, and the crybaby sadists. I mean, their differences are definitely there but really if I had to choose favorites, it would probably have to be because of the way they look and how they are stereotypically having to act.

The mansion setting feels like a haunted sims house. You got a mansion with 50 rooms and yet somehow all they do is bit Yui in same 3 spots (library, hallway, bedroom) and repeat.

In short:
Diabolik Lovers is Twilight's evil twin. All the bite, none of the heart. A toxic mess dressed in beautiful animation, where plot goes to die and red flags throw a rave.