I wrote a brief response to David M. Armstrong's criticism of Berkeley as found in the editor's introduction to Berkeley's Philosophical Writings (1965, 1980, ISBN 0-02-064170-2). It's just a brief overview, but I don't know if I'll ever get around to fleshing it out, though, so here it is in its current form. Feedback is always appreciated!
P.S. The original essay (the one by Armstrong) is also available here.