I personally think they're excellent. I mean, if you're not into being creeped out then I'd probably avoid them, but if you are then the stories and art work kind of pull you in. If you've read some of High School of The Dead and didn't mind the gore or the psychological aspects, all three of those Manga take it a step further and really push you in a direction you'd rather not travel towards, but you can't help pushing further into it.