I'm really liking this series, but only to a certain extent. It's another one of those "MC reborn/brought into a fantasy world to become powerful and gather his own harem over time wish-fulfillment" kind-of-stories, and honestly, I've gotten pretty tired of seeing so many of them shat out over the past two years. Luckily, this series has our MC take on the role of the OP villain rather than that of the rising hero, and oh-boy does it work well in this one. To be exact, whenever the MC acts like a terrible person, well, it makes sense that he of all people would be like that. He's incredibly manipulative to both his foes and his friends, and it really does fit his character perfectly. So if you're the kind of person that doesn't want to see a protagonist manipulate practically everyone around him in attempts for gaining power, then this is proooobably not gonna be a fun read for ya...
For a little more background, what we have here is basically in between Re:Monster and Overlord: An MC that's working on amassing his own personal fighting force that will be unstoppable, all while being completely overpowered right from the get go. In this case, the MC gathers humans, demons, monsters, dark elves, dwarves, etc. etc. to occupy his ever-so-growing dungeon. For those that stand in his way, he'll either bring them to his side, or simply kill them immediately. At the rate things are going, it looks like it'll be a fun ride to tag along on.
However, as for why I'd consider this to be an "incredibly bad series," I've gotta say:
The art is kinda bad. Well, the character designs are pretty above decent, with the girls being cute and sexy and whatnot. The action as well is ok-ish, despite there not being much shown yet at only 6 chapters out right now... The big issues though are that the monsters aren't very impressive when aiming for variety; the backgrounds feel somewhat nonexistent, and yet they're pretty much building the very dungeon they live in from scratch (which would've been quite nice to have seen the development over time, but it's too late for that now...); and the "chibi" characters look pretty lame whenever they're shoehorned in for every damn joke the mangaka tries to throw in each chapter, which I'll admit is a heavy personal dislike toward the style choice that they decided to run with.
In comparison to the previously mentioned series, this one's definitely got more balls than Re:Monster could ever manage to muster. It's willing to show off humans being killed by our dark protagonist and lots of sex when possible, while RM's won't show the killings nor any sex at all. As for Overlord, the art in this series definitely doesn't feel as crisp and clean which is a shame to say the least.
Ending on the topic of sex, I worry that there'll be a stupid "quota" put in that'll end up taking away from the series as the story goes on further. So for just about every female character that becomes his ally, they'll probably end up wanting "The Hot Dickings" from him, shown at least once per chapter. Now don't get me wrong, I don't hate on sex and harems, but if this devolves into an all around mess like Ookii Onnanoko wa Suki Desu ka? became, guess I'll have to jump ship a second time...