Story:
Big Order's story at it's core, has everything you would need to make a great anime. But with only 10 episodes and since some of them feels like a fillers rather than anything else, it just couldn't deliver it. So it just feels rushed and ideas are picked and dropped like flies. More than that, many plot point are forgotten just after they happen and characters, especially the main character seems to keep forgetting his power when it would be most useful.
Art & Sound:
Art is good and sound is not bad either. But there is really nothing that stands out. Some of the concepts used would be better if they were executed properly, but unfortunately they weren't and some of it turned out to be annoying in the end.
Characters:
There isn't much character development to talk about. (well, two of the characters developed a bit, but in the end they were still shallow.) While some characters are decent enough, others seem quite shallow and some of them outright ridiculous. Their motivations are all weird as well. They seem to change what they want and their motivations or rather keep forgetting them every next second. Main character seems to suffer the worst from this but that's not the worst example, like I have said, there are only two interesting characters in this anime who gets some level of development and this ruins them as well.
Enjoyment:
It really isn't terrible as some would suggest. I really enjoyed some moments of it. It certainly isn't great, but it could be considered something to watch if you have some time to kill and nothing better to watch.
Overall:
While it isn't as terrible as some would suggest, it certainly is mediocre because of its wasted potential and how disappointing it was. It has very little rewatch value and while it had some sort of happy ending, that was disappointing as well. In the end, this anime is flawed at the core.
