Michael Oakeshott once said that reality is "not whatever I happen to think; it is what I am obliged to think". And for Berkeley, what one is "obliged to think" are the thoughts in the mind of God. The question any idealist metaphysics must face is, "Why do we seem to perceive a common reality with certain intractable features?" Berkeley may not have answered that question in a completely satisfactory way, and perhaps other idealists have done better. But he did provide an answer, and that answer is why, in his view, (human) experience is not "radically subjective", but is an objective world of ideas.
Hilary Putnam, in Renewing Philosophy, discusses the final arrival of esteemed analytical philosopher Nelson Goodman at a sort of radical relativism: "But if we choose to speak of worlds, where do these worlds come from? Goodman's answer is unequivocal: they are made by us. They are not made ex nihilo, but out of previous worlds... Springing full-blown within contemporary analytic philosophy, a form of idealism as extreme as Hegel's or Fichte's!" (1992: 111)
Never mind that Putnam is almost certainly misreading Hegel and Fichte; his point is important nonetheless. I would not wish to suggest for a moment that Berkeley is the last word in metaphysics. If, for instance, someone rejects his concept of God, Berkeley's basis for the objective reality of the world goes with it. But he was surely correct in arguing that it was the posit of an un-sensed matter, without color, texture, warmth, tone, feel, or character, a "something we know not what"—what Whitehead called a "vacuous actuality" (1969: 193)—that pointed the way down the road to skepticism.