On one hand it’s an enormous forward expansion of knowledge. You do learn a lot. On the other hand it doesn't leave much time for the kind of lateral thinking and linking together of unrelated thoughts that gives rise to new insights.
In the debate between graduate school and the job market, I'm currently leaning towards job hunting. Yeah it's cool that grad school is now a real option, but school just does not leave me with any time for writing. Since getting published has been my life long dream, now is not a good time to turn my back on it.