I'll start my personal review with big words: In my personal opinion made in abyss is the greatest universe of all time.

World and art style: 8/10

This world is so big and interesting, art style of this show may look a bit childish, too colorful and boring, but as soon as you will experience complexity of nature, cities, artifacts, and even small things, like equipment of protagonists you will definitely change your mind.

Story: 7/10

Story is simple and clear, but still not predictable and boring. In fact simplicity is, which makes this story even better, because it leaves space for things such: Character development, many plot twists and great action.

Characters: 9/10

Protagonists are awesome, especially emotional bond between them, that tightens after every problem they face.
Antagonists are great too, but you won't see them that much, since protagonists are dealing with more difficulties trying to survive in wildernesses of nature. But when they finally face someone hostile, the fights are interesting and different.
Supporting characters aren't that interesting, except Nanachi.
The pros: um, they’re really cute! There’s the juxtaposition created by putting naive, driven, and weak protagonists in a dark and cruel world.

Music: 9/10

Incredibly great and novel sounding. It's also been mastered well: listening with good headphones, you can hear that some parts are louder, and some are quieter, which the audiophiles definitely enjoy.The only criticism I can really come up with is for "The First Layer." The piece itself is fantastic, and fits extremely well in a lot of scenes. But dare I say... it's a bit overused in the series.

Atmosphere: 9/10

"One of the biggest thing that the anime did well in this respect is the sense of tension. The bird’s eye view shots give the viewer a good sense of the abyss’ depth and shows how Reg and Riko are just two tiny beings dangling from the sides of it. Every move the two make is a risk – even regular scenes of them walking or talking can be intense to watch when the characters are suspended or treading casually on unstable paths. Because of this constant tension, at no point while watching this anime did I feel bored." -moyatori

My thoughts:

First time in my life after completing anime I came to conclusion, that this universe should at least have: game, Film (not animated) and most importantly something like guide book, that explains some things about made in abbys world, that haven't been shown in production, such as catalog of all artifacts, informations on different creatures living on each layer and more. "What I appreciate most of all about Made In Abyss though is its emotional honesty. In an era where it’s not very cool to put your heart on your sleeve, and most anime attempts to jerk your tears so hard they’re on cables, Abyss was a beautiful example of what you can do with skilled writing, top notch production and organic, sustained character development. While it’s both sweet and brutal, this doesn’t mean that it’s a schizophrenic beast snapping from one to the other, as so many pieces of fiction tend to be. Rather, Abyss immersed us in its world and then refused to turn away from moments both beautiful and horrifying, wrapping our story deep within its own world."- Zigg