GRAD SCHOOL: WORTH IT?
Invisible Adjunct has two posts on the subject, here and here. The gist of her analysis is that people need to go into grad school, especially in the humanities, with their eyes open and actually think about finances, including the opportunity costs (years of lost salary while in school).
Thomas H. Benton, writing in the Chronicle of Higher Education, has similar advice. His number one rule is not to pay for graduate school–which means only going on a full assistantship and not getting lured in on one-year fellowships. To gain negotiating power, he suggests applying to at least ten schools and then playing them off one another.
Brian Weatherson has done some research and finds that, at least for Philosophy majors that can get into top programs, the opportunities aren’t bad at all.
So, to recap, go only if you can get into a top-tier school, if you can go for free, and if you want to study Philosophy. Otherwise, do something else.