Let's get the easy stuff out of the way. The animation is of course, top-class, with great imagination in the design of the world within the abyss and it's creatures and phenomena. Voice acting is equally competent, although I rarely find any anime in general to be lacking in this. Music is the pensive melancholy unique to the show, but since it's a western composer, it tends to be more ambient and lacking a strong melody, which suits the show fine. Contrary to what some have said, the sense of dread, awe mixed with fear and wonder, is fully intact, each new encounter always eliciting a sense of insecurity and trepidation, instead of safety and boredom. Also contrary to what some have said, there are real consequences and weight, even if many of the characters seem to brush it all off with childish optimism. They don't dwell and rationalize like adults do, and are far more flexible in their thinking.
I did consider the first season a bit overrated, especially when it came to a logical plot or character interactions and emotions, but I was able to enjoy the movie more by lowering my expectations, turning off that part of my brain constantly looking for plot holes in the immediate story. It's like playing Dark Souls. The actual lore, when explained, is really stupid. And character interactions are odd and obtuse. But the "environmental storytelling", the atmosphere and mystery of a strange and unknown world far removed from your own, with hints of people, places, circumstances, and supernatural beings alien and unfamiliar, is the main allure. It would be great if a compelling cast or tightly woven plotlines accompanied it, but it's not necessary. You turn on the music and let it wash over you, deep in your own thoughts. The artist might be thinking of making sausage tacos and buying organic lentil snacks at the market. It's not relevant to you.
Regarding the actual plot, well it's about what you expect from the series. A twisted villain with a goal far beyond the comprehension of the viewer, grandiose and fully engulfed in their own mania, erratic and unpredictable, with his own set of unconventional values about love, family, and purpose. The robotic voice inside a mask and the many abilities he has makes him very similar to All-For-One, the villain in My Hero Academia, including the philosophical ranting. Made in Abyss is far more grisly with it's portrayal of chopped body parts, human bone tools, and explicit infliction of pain and suffering, but it maintains a lighthearted whimsy and juvenile ignorance that keeps it from being sappy. If you want real drama, this is not the show for you, outside of momentary shock value. The children are just vessels to illustrate the brutality of the Abyss and not characters to invest into.
