The character art and designs were pretty bad, as was allot of the animation. The story was also fairly contrived in how it had to use Rakka not getting useful information just so she could suffer over not knowing later on. Rekki's hidden motivation was'nt all that well demonstrated, we just got that idea about her character thrown at us at the end through dialogue, which was kind of sloppy.
It has nice background art, pacing, and themes though. And it did an excellent job not over explaining the setting, instead allowing obtuse mythology to give the questions about the world some answers, but leave the mysterious element of the journey through the story intact, which helps it connect with real existential questions that don't have cut and dry answers. The characters themselves were very easy to empathize with too, which was nice.
Ultimately it was a good but heavily flawed show.