After I read your initial post I did some searching of my own and the only real criticisms that I found (other that she is an overly critical proscriptive curmudgeon) were references to that same New Yorker article. I was not able to find a copy of the article itself, but references to it seem to excuse most of the criticisms as originating from the differences between American and British use of punctuation, particularly the semicolon. Apparently we went through a bit of a reformation and standardization that never took root across the pond.
The one criticism that seems to be mentioned any time someone refers to the New Yorker article is the lack of an Oxford comma in the title of the book. Serial commas are not even standard for everyone in the states, and are apparently much less common in England, yet it is always described as a punctuation error. I think this is as case of one punctuation Nazi fighting with another over who can be the most anal, but if there is some other problem with the book please let me know.