First of all, with these 12 chapters you won't get a full story. I think it got axed, because it could go much further, but unfortunately it ended really abrupt. So if you don't want to read an incomplete story than don't read this one. Also due to this incompleteness I rate it lower than it maybe really was. (I'm not a fan of incomplete stories, no matter it got axed or not)

Story 5/10
In these 12 chapters you get an overload of really good ideas and topics. I mean, you get a post-apocalyptic (partly) sci-fi action-adventure mixed with lot of politics/religion and their issues... This is a bit much and really overwhelming, especially in just a few chapters. Of course this is one of its strong points what it makes the work interesting, however, it is still too much and you easily get lost of the track (who is with whom; why they do this... etc.). And this wouldn't be a problem if it had at least 20-30 chapters more to get more in the detail, but it don't.
The same goes for the special setting (what is supported with the art), a world where there is no light from above (so literally no sky) and simple-minded people who fear the "relics". The basic idea is really good, but it lack of time/chapters. Don't misunderstand me, the story is not rushed, if any it's slow paced, it just ended with a lot of unanswered questions... So at the end, you will have a feeling like this whole Manga was just a trailer, a preview or a intro for something big.
If it would be complete I think it could be at least a 7 or an 8, so now I just appreciate the great ideas with a 5.

Art 5/10
The art is a hard one... You should know, it is a colored manga, and not everyone is a fan of it. However, in my opinion you need colors for this setting. There is a lot of darkness and it would be strange if 80-90% of the manga background would just be plain black... So with these, it has a "third dimension" to work with. But on the other side, it feels less a manga than a "american comic". So I have mixed feelings too. Also, and that's hard to put in words, something kinda feels off... The action was kinda slow, the lines were kinda static, I missed somehow the dynamic... But maybe it was just because it was colored... So I'm a bit unsure.
So, I wouldn't call it bad, but either good. If you like colored mangas or "american style" comics you may preffer this style. It's a matter of taste at the end.

Character 2/10
In 12 chapters you won't get character developments and you won't really get to know them... Also you may get 2 Characters which has more than 3 chapter screen time, so yeah... In addition, I wouldn't just say it's the problem of the shortness, I also think ANGYAMAN (the mangaka) not really cared enough for a character development or for a more detail rich background for them. So this one is really missing something.

Enjoyment 6/10
Interesting story and setting, a really good mix of genres and even if it was a bit slow it had a good pace. So it was enjoyable and you really wnat to read more, especially with this ending, however, with this abrupt end it pushes your enjoyment down. With at least a proper ending (and there was the chance for that) it could be better even with 12 chapters.

Overall 5/10
It's incomplete and don't have the usual "manga vibe". Then on the other hand we have a lot of interesting things, setting and topics. So speaking for myself, I have mixed feelings for this work, but it wasn't wasted time.
So if you don't care that it's incomplete and isn't like the mangas that you are used to, then go for it if you like more mature and serious stories. But if you are into light stuff, searching for something funny or simple-minded action-adventure and especially if you don't like incomplete stuff, then you can spend your time better.