Allen Allentuck (reviewing the book in Quill and Quire) felt that:
The scope of The Merchants of Venus is astonishing: it contains a history of paperback publishing, an analysis of romantic fiction, examinations of book distribution systems around the world, biographies of numerous publishing bigwigs like Richard Snyder of Simon & Schuster, and, of course, a chronicle of the growth of Harlequin.
It is primarily a business/publishing history of Harlequin as a company and although I've listed some authors discussed, Grescoe writes at much greater length about Harlequin executives. Kathleen Gilles Seidel in "Half-Risen Venus," Para.doxa 3.1-2 (1997): 250-252 raises some issues about Grescoe's sources. Seidel, who mentions that "the first six of my ten books were published by Harlequin" (251), acknowledges that Grescoe has "written a lively account" (250) but feels
Grescoe often seems unaware of when he is talking about Harlequin/Silhouette and when he is talking about the romance community in general. Many writers he interviewed have written for other companies as well, and often only extremely careful reading - or independent knowledge - reveals that he has slid into discussing their work with the other companies. [...]
Grescoe didn't do his homework. His information about contract disputes comes primarily from PANdora's Box, a relatively recent Romance Writers of America newsletter for published authors. He is, therefore, unaware of many older, far more significant problems. Relying heavily on interviews with several Harlequin executives and former editors, he has little context for questioning their versions. He allows to stand, for example, Brian Hickey, president and CEO of Harlequin, taking "credit totally" for the Tyler "continuity series," books by different authors about the same group of people. An informed observer surely would have given considerable credit to three Bantam authors - Kay Hooper, Iris Johansen, and Fayrene Preston - whose books about the Delaney brothers were the first such series. Immediately following the staggering success of the Bantam books (and before the Tyler authors were approached ) Harlequin editors called groups of their own established authors and contracted them to write connected books within the existing lines. Grescoe seems to know none of this. (251)
In addition, archivist Steve Ammidown has expressed concerns about some of Grescoe's statements with regard to the career of Janet Dailey:
According to Paul Grescoe’s book The Merchants of Venus: Inside Harlequin and the Empire of Romance (1997), it was 1976 when the Boon brothers, who were based in London and held a stranglehold on the content of Harlequin and Mills & Boon despite being fully part of Harlequin Enterprises by this point, decided to break with tradition and publish an American author, putting out No Quarter Asked as Harlequin Presents 124. Dailey’s official publisher bio uses this date, as did the New York Times obituary published upon her death in 2013. [...]
You see, the problem is that Paul Grescoe is wrong. And so was Janet Dailey when she repeatedly told reporters that her first book came out in 1976.
Huh? How’s that possible?
Good question! You see, the agreed part of the story is that Dailey did in fact send her first manuscript to Mills & Boon in 1974. We don’t know if they did request any changes (Mills & Boon’s editorial practices were notoriously lax), but Mills & Boon turned around and published No Quarter Asked in 1974.
In fact, Dailey would go on to publish 7 more books for Mills & Boon before her work was shipped to Harlequin as part of the Presents line in 1976. Dailey was in fact the first American woman (who we know of at least) to write for Mills & Boon since the company’s founding in 1908. A not insignificant moment for American romance authors!
What Janet Dailey was not, despite her claims to the contrary, was Harlequin’s first American author. Prior to 1964, when Harlequin began exclusively reprinting Mills & Boon books, the company regularly published American authors of romance and other genres. The very first Harlequin title in 1949 was in fact a reprint of The Manatee, by American author Nancy Bruff.
These details, and discussions of the consequences of accepting erroneous information can be found at Steve Ammidown's website.