I have not yet read the book, though probably will at some point, but the New York Times review is very much written for readers more used to popular history of the type that you see from Barry Strauss or (ugh it pains me to say it) Tom Holland. The reviewer's comments in the paper very much were aimed at pointing out that the book, as is usual for Mary Beard's work (she is a social historian, after all), attempts to point out things that are not often touched upon in popular histories. Is it new? Possibly, I haven't read it. But I find it unlikely--as you say, popular histories are generally not where innovation in the academic world first appears (although popular history can often be a revised, popularized version of work previously submitted to an academic audience--Kagan's popular history of the Peloponnesian War is a revised, abridged version of his enormous academic study on the same subject). From the review some of the things that Beard said are decidedly not new to the academic community--her characterization of Actium as "a rather low-key, slightly tawdry affair" is something that Syme famously pointed out in The Roman Revolution, for example. But it is not necessarily something that is common among popular historians. Beard's quoted remarks about Gibbon, I think, explain the purpose of the book, to bring to popular history--for most people the only history that will ever be read--a much more up-to-date view, one that resembles the academic process much more than the antiquated thinking (sometimes over a century out of date, in the case of pop histories of late Republican Rome) of many pop histories. But again I haven't read it yet--this is all just my impression