Story: I will never look at spirals the same way again, and never did after reading this. Or snails. Or hospitals. Quite frankly, this is some disturbing shit. It doesn't simply create a shock scare or two, you see it gradually going to shit, the transformations of the spiral, the horror that is right there infront of you. It doesn't shirk on that front and that just makes it even more chilling.
Bone-chilling, as some of the chapters are simply nightmarish. Transformation body horrors first and foremost, with some blood mixed in for good measure and a dose of Vitamin Die. Too many chapters to list, but it's filled with varying degrees of mind-scarring disturbiness. The price is that sometimes, it doesn't work and a great chapter can be followed by a lesser one. The author isn't shooting the head with all six shots of the revolver; some miss the killshot and tickle a bone or just a mere graze.
I'm only talking about the horror because that's why you're here. The premise of spirals fucking everything up is neat and all but the horror, body disfigurement and all the weird shit the mangaka came up with are the main attractions. You aren't here for much else, so horror or take the next bus to shounen town.
Art: To compliment the horror is equally horrific art, in the good sense. It may be a tad dated but it still presents the horrors within this cursed town. The curse of the spirals manifests itself in many ways, horrible and disturbing. Outside of that, things are fine and dandy but not... as eyegrabbing, I guess. Once again, it's the black flowers to the skeletal tree with branches of blood fruit, so to speak.
Characters: Kids back then sure were dumb. Once that freaky shit started up, I would have fucking gotten the fuck out of there, just run and never look back. That's what she should have done, but crazy shit keeps on happening to her and she still stays there, alive, relatively unharmed compared to other poor saps. But you can't help but feel sorry for her, despite her inability to be genre-savvy enough to get the fuck out.
And there's the guy, who might have been a bit smarter but still dumb enough to stick around.
Gah! You aren't here for the characters! It's the events that they're put through that you're here for! Know what? I'm wrapping this up.
Overall: Some damn good stuff. Disturbing, creepy, unsettling and one of the most fine ass endings I could hope for in a horror manga. It's worth getting some brain bleach for your poor mind just for the ending.