I think that unless a reviewer gets their facts completely wrong, the author should shut up (and even then, the author should probably let it go - although I'm a big fan of a letter that James Branch Cabell wrote to the New York Times pointing out that their review of Figures Of Earth was bollocks. ... For most authors, not being James Branch Cabell, it's probably wisest after reading a particularly stupid or vicious or bad review to mentally compose your letter to the editor, fill it with your sharpest and most cutting and brilliant bon mots, and then, having made it up, to successfully resist the urge to put it to paper, and to return cheerfully to work.