A lot of reasons, primarily Bitcoin related, of course. It's a community of people who all seem to share a similar disposition as me. Young site, which gives it a tight-knit community feel, and of course the lightning voting system which forces a user to put their work where their mouth is.

Aesthetics, information, entertainment... I could go on. But that's the core of it. It's perfect to me, and it's something unique to(in?) my lifetime.