I think the biggest problem I had was that I mostly caught rerun episodes in the afternoons that were shown in no order that I could discern. So one day it'd be Season 6 Buffy followed by Season 3 the next = whiplash from changing moods & tones.

Oddly, I've never really been in Buffy fandom, although I'll read the occasional fic. Same thing with Firefly, although I adore the show.