It really is a unique series with an interesting story and has a distinct signature feel to it. This is something that is not easily obtainable these days, especially in such a over-saturated industry.
The studio behind it, Kinema Citrus, Which until now has had a somewhat iffy record in adapting content in anime have done an excellent job in adapting it. I give my applause to the animation crew for making the world of Made in Abyss looking so real and alive, the art style really captures the moment like you are seeing this wonderful world in all it's glory.
Like many others have said, the only real downside to this, is that it is left unfinished. However that is to say the adaptation was not good. They did a solid job in adapting it and as far were it could have been chosen to end it, they left in a pretty solid end zone, easy to pick up from where it was left by reading the manga.
I just hope than when enough content is out, they can continue to animate it and with the same team again as they did a good job with it.
