I'll get this out of the way first: the appeal of Diabolik Lovers - both as otome (reverse harem) games and as an anime - is being forced into a relationship with unstable, cruel, and violent boys. This isn't an accident. The show isn't unaware of the power dynamics and metaphorical rape (through non-consensual erotic blood sucking) that happens. The cruelty is the point. The romance basically boils down to a series of CNC (consensual non-consent) fantasies through which, the love interest begins to like you, and you "fall" to being just as depraved as them.

If that's not your thing, then don't watch. And if that is your thing, play the games.

The Diabolik Lovers anime has the same premise as the game, but it needs to fit six different, complex, violent, horny routes into 12 half-length episodes. The show, as a result, is more of a highlight reel of scenes from the game. Most of the earlier episodes focus on 2-3 scenes; Kanato's graveyard kiss, Laito's church assault, Reiji poisoning Yui, etc. There's little plot, and it's essentially pure fan service. The fun is seeing scenes from the game animated on an anime budget, and if you're not already a fan, I imagine the first two-thirds will be a slog.

This leads into a wider issue with the show itself: the pacing. Since it's a highlight reel of six different routes, there's never any downtime. As soon as one abuse scene ends, another character walks on screen and starts his own abuse scene up. There's never any breaks or buildup, and as a result the hotness of the scenes falls extremely flat.

So, it's got pacing issues and is a poor adaptation of an already niche game. Would I recommend it to fans of the game at least?

Well, it depends. If you want a serious adaptation, no. If you want a bizarre, confusing relic of the past (made before even the second game came out) and/or want something to laugh at, then yes.

The narrative changes from the game are bizarre. There's a strange focus on Richter as the primary antagonist. Ayato is picked as the main "canonical" love interest, and some of the boys - Subaru and Reiji in particular - really get shafted by the narrative. The ending is bizarrely happy compared to the actual game, and even if your fav is in the spotlight, you may not want them there with how odd the art style of the anime is. Everyone looks profoundly off, and while I think it's funny, I could imagine a diehard fan getting pretty upset that their scrunkly is all weird and ugly.

Ultimately, this isn't a good anime nor is it a good adaptation of the source material. And, as evidenced by the other reviews, if you're sensitive to or not expecting comically violent, horny, abusive scenes going into it, those might really throw you off. However, as a DiaL fan, I think there's some stuff to like here. Not only is it a peak into an alternate "what could have been" future for the franchise, but it's really fun to make fun of.