I know, this sounds mega cheesy, but I actually have learned a lot from Anya, the main being that sometimes you need to say what needs to be said, no matter who gets hurt; truth hurts and thats one of those life things.
From Buffy herself, Ive learned that life sucks basically, but you cant give up, you've gotta stick to it.
From Angel, the show, Ive learned you cant trust everyone, and as back-stabby as that sounds, its very true.
With Willow, it was great with her addiction, and the metaphor for drugs, I mean, Ive never tried drugs, and never will...or I dont plan to, but at least I know, that if for some reason I do, you can get out of it, all it takes is patience.
If it wasnt for Buffy the show, I would've killed myself by now, watching the show, and everything that all the characters went through has made me a stronger person, and Ive learned to appreciate things better...
Im so happy with everything that Buffy, as a show, has done, and I wouldnt change a thing!