I usually don't read manga. I don't read them on their own and neither do I pick them up after the anime has finished. But the anime for made in abyss made me want more of it SO BADLY that I devoured the 6 available volumes in less than 2 days. And I do not regret it at all. I have never read anything quite as entertaining as this, the artwork is original, impactful and doesn't shy away from the more graphical side of the brutality that's going on. Speaking of impactful: Being a show about going down a highly hostile hole (alliteration intended) there aren't that many characters, but those characters that DO exist, are written and designed really well.
As I mentioned, since I devoured it so quickly, I'm now eagerly awaiting chapter 43 like I'm a junkey who's waiting to get another fix of drugs...

I personally enjoyed it because the balance of fun and seriousness was spot-on. There is enough light hearted fun to not make it seem like sufferporn, but also enough gore and violence to probably get it age restricted almost everywhere. It's a fine line and the author manages to walk it to perfection.

The last arc that has ended was almost too screwed up for my personal taste though, but I still highly enjoyed it. It's just REALLY disgusting at some parts...