Great opening chapters, strange and inconsistent middle chapters (with good, unsettling moments), and a cohesive ending in my opinion.
I really liked the ending. That the Spiral remained unknown force beyond human comprehension and they were powerless in the end after putting up a lengthy, horrible struggle.
Kirie came full circle for me with her decision to stay with Shuichi amidst the hopelessness, because I have come to the conclusion that Shuichi stayed and suffered for Kirie even if he could have seemingly easily left at the beginning of the story. A touching sequence that depicts love can last even amidst the bleak unknown.
Though one could argue Kirie had nowhere else to go, I like how she made that conscious decision rather than losing herself to madness.
Manga was a little overrated with all the hype surrounding it, but it was not a bad work by any means. Questionable story beats and character development aside, this read was overall enjoyable.