TL;DR: Creepy, be ready for some twists. Dark and mature themes. Inconsistency with the art style, but can usually be ignored.
Did you watch the first episode and go "meh"? Watch the second episode and said "ehhh..."? Yeah, me, too. For whatever reason, probably my insatiable curiosity, I stuck with it.
Shin Sekai Yori has a subtle seductive quality: you don't realize that you've been