This link was posted at Whedonesque today, an excellent piece by the British critic Clive James...it's a bit dated (written circa 2001/2002) written probably during season #5, it erroneously describes Faith as dead, and doesn't address the Buffy/Spike relationship or Joyce's death but otherwise is a wonderful insight into the Buffyverse. I was glad to see his mention of the influence of the existentialism of Sartre (those that know Joss realize the influence Sartre's writings have had on him). Pretty much right on target in my opinion!
http://www.clivejames.com/articles/zoe/vamp