I think it takes the concept of Mahyana and extends it to its full fillment from and I or egocentric point of view. This being that everything is illusional and an extension from true mind. To me this is egocentric in nature. This is where the fundamental teachings of Buddha took a left turn.
Emptiness is simply stating that nothing exist without relivance to something else. That there isn't any inherent existance of anything in this world. Or in other words everything is interdependent in its fundamental nature.