Is this a great court?

In this article in the California Bar Journal, J. Clark Kelso states

There is no doubt that the majority decision pushed the ball down the field a little further than the California Constitution necessarily required. But that, after all, is what leadership is all about. That is what differentiates a great court — a court that is a full participant with the other branches of government and with the people in developing more mature understandings and interpretations of constitutional provisions — from other courts.

Using these criteria (leadership, great, mature, and participation), how would one decide that the court went too far or went in the wrong direction?