I'm going to assume you're going to watch this knowing that it's a Japanese modern-set fantasy production. You may or may not know that it's based on Japanese manga; I am not familiar with the source material at all, I just happened to see that it was based on some when doing basic research on whether to bother watching it.
If these kinds of things aren't your cup of tea, don't watch it. It's science-fiction-ish but really it's done kind of a minimal science fiction plot to explore some character and human nature themes.
For being within that genre, I thought it was quite decent. The English dub was OK; the main issue I have was a lot like a problem I have with many anime titles, the closed-captioning subtitles and the English dub were not in sync. But that's maybe OK since you can get more information about the source material to see two different translations. (OK, it's really just annoying but I'm trying to make lemonade here.)
The games / puzzles that the characters end up having to go through are slightly obvious, our hero should have figured out a few of them in an instant. But whatever, plot rulez. I still recommend it. 8 might be overly strong but I think it's a good series and being an adaptation of existing IP, doesn't seem to cut many corners.
Maybe followers of the original manga have tons of problems with it, they usually do, but on its own, I liked it, I'm very glad I watched it, and I am looking forward to the next season or whatever we call them nowadays.