Made in Abyss is odd, not only because of but in spite of its creator. Tsukushi Akihito is an, uh, L word and also an S word, meaning that themes of child exploitation are front and center. And while I'd normally knock a work for that, it somehow works here.
The society on which Made in Abyss focuses is one that holds life fairly cheap. Children are taught that the ultimate good is exploring (and exploiting) the aforenamed Abyss, a seemingly infinitely deep and mysterious pit around which the subject society's culture is quite literally and figuratively built. The Abyss is a source of technological and societal advantage, while at the same time being a literal pit of despair and eldritch horror.
Our main characters are Riko, the twelve year old daughter of a very famous Abyss explorer and Reg, a childlike android from the Abyss itself who has no memory. The story mainly focuses on subjecting the pair to varying levels of Lovecraftian horror as they attempt to explore the Abyss. That's it, that's pretty much the plot. These kids get run through the wringer while trying to survive. So why exactly do I like it?
Well, despite the deeply L an S elements, this is a series that takes the plights of all who enter the Abyss very seriously. The Abyss is a masterfully crafted, existentially threatening place, with little comfort of solace to be found in between our main cast running for their lives from some cosmic horror. The Abyss itself is an existential enemy, and the farther one descends, the more it takes, both literally and metaphorically, from you. So, wile it has flaws, Made in Abyss is extremely gripping. One wonders how someone could conceive of such a place.
Beyond this, the characters are actually quite well realized, from our main cast of children to the adults with whom they must deal or navigate around. No one in this world feels static, and every on-screen character has a role to play in the story.
I have lots of criticisms, too, but I almost feel as though they don't matter. Any critique I could offer is almost irrelevant. If you like the series, as I do, those issues aren't worth mentioning. If you don't like it, you'll drop it. But the series is a unique and uniquely twisted and once again Lovecraftian saga, and one that you'd be remiss in at least exploring if you enjoy cosmic and existential horror coupled with the perhaps most twisted slice of life ever put to ink and paper.