Michiko Kakutani is the NY Times lead book reviewer. Her reputation as a book critic is simply enormous -- her predecessor at the Times (Christopher Lehmann-Haupt, who still writes reviews) and her colleague (former movie critic Janet Maslin) do not even come close to the power and influence she holds. Indeed, Kakutani is essentially the book critics' equivalent of Frank Rich in the 1980s, who could make or break a broadway show with his review, or Anna Wintour, the famous Vogue editor whose influence in fashion is legendary (four words: The Devil Wears Prada).
Among the reviews she has written, before today Kakutani has issued six reviews of Rowling's Harry Potter series. Each one glowed. Kakutani's praise is hard to earn, and more difficult to continually obtain (ask Frank McCourt, author of Angela's Ashes whose follow-up 'Tis got panned). Rowling has achieved this rare feat -- each of the six reviews praised the Harry Potter books lavishly, at minimum. That praise, especially for books one and two, gave an inestimable boost to the Harry Potter series in the United States (remember, no movies at that point in the late '90s).
Thus, Jo Rowling's complaint that "I am staggered that some American newspapers have decided to publish purported spoilers in the form of reviews in complete disregard of the wishes of literally millions of readers, particularly children," is ill-taken. Kakutani has, in no small measure, helped Rowling's career tremendously. Children tend not to read the NYT book reviews. And given that book 7 is no less highly praised than the previous installments, this criticism is baseless. Unlike the ding-dongs who put HP7 online in one form or other, the minor plot outlines from Kakutani and other reviewers are hardly "spoilers." Better to complain about those folks than the reviewer who helped launch the HP franchise in the US.