As a writer you have no way to respond to a bad review without making yourself look like an arse.
Best case is to thank them for their review and say you will look into correcting any errors that the reviewer found, if they email them to you. I will be frank and say, you do get fed up of Reviewers that seem to get hung up on grammar or spelling, and at times just want to know if they enjoyed the story or not. Did the story entertain you, yes or no?
I am myself under the opinion it doesn't matter how many times you go through your work, how many Editors look at it something always slips by. Every time I read The Lord of the Rings it justifies my thoughts on proof reading, sometimes the littlest things get away from you.
I read this blog yesterday, for the Author in this case the best course was total silence. Now its a small viral hit.
Arigato,
Nick Davis