Nobody's perfect. Not even Vintage.
If you look closely (click to make the image larger), at the blurb from Kakutani's review from the NYT, you will see that the first sentence reads, "One of Roth's most powerful novel's ever..."
Now, before you jump on Kakutani for having bad grammar, I hate to tell you, but the New York Times must have better editors; this mistake was Vintage's.
I wish I could claim finding this juicy tidbit, but I stumbled across it on the always insightful and entertaining blog Book Covers from the NY Times Book Review. Read more.