What is the flaw of George Berkeley's philosophy?

Answer 1

A flaw:

The word 'nothing' was given equal meaning, standing or value to the word 'matter'. The word 'matter' does have utility as in respect to the energy concept in sub atomics; matter is destroyed to energy and energy constitutes matter, but neither may be reduced nothing or non-existence and hence the misuse for the word 'nothing' as synonym for all existence.

http://www.marxists.org/reference/subject/philosophy/works/en/berkeley.htm

'80. In the last place, you will say, what if we give up the cause of material Substance, and stand to it that Matter is an unknown Somewhat - neither substance nor accident, spirit nor idea, inert, thoughtless, indivisible, immoveable, unextended, existing in no place ? I or, say you, whatever may be urged against substance or occasion, or any other positive or relative notion of Matter, hath no place at all, so long as this negative definition of Matter is adhered to - I answer, you may, if so it shall seem good, use the word 'Matter' in the same sense as other men use 'nothing', and so make those terms convertible in your style. For, after all, this is what appears to me to be the result of that definition - the parts whereof when I consider with attention, either collectively or separate from each other, I do not find that there is any kind of effect or impression made on my mind different from what is excited by the term nothing.
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Answer 2

For him, there is no existence independent of subjective perception (esse est percipi), the apparently ordered physical world is the work of God. I respect his own philosophy.

Answer 3

Samuel Johnson refuted it by kicking a rock -- see Boswell for the details.

Answer 4

there is nothing wrong with his philosophy, there is a flaw with philosophy itself.