From the New Oxford Review back in December 1994.

Writing the history of a reli­gious institution involves under­standing concepts and language within their historical and cultural context. Otherwise, the risk is taken that history will be rewritten to suit current preoccupations. Boswell’s attempt to prove that the Byzantines regarded adelphopoie­sis as a form of marriage fails be­cause his research presents histori­cal facts and events out of context. From Boswell’s viewpoint, it would appear that matrimony is being cel­ebrated when two individuals are united by a priestly blessing in a ser­vice using symbols held in com­mon with marriage ceremonies. However, Byzantine marriage was celebrated as a process that united families as well as spouses in a se­ries of rituals, not in one rite that mainly affected its participants. Simply put, adelphopoiesis was certainly a kind of union between two individuals, but to make this institution equivalent to matri­mony necessitates a perspective and context foreign to the late Byz­antine Church.

Go read it all to get the full argument.

Consider when this was published. December 1994. Strong demonstrations of why Boswell is very wrong on these matters have been around for 20 or so years. And yet Boswell’s historical revisionism keeps being regurgitated. At some point there’s just a lack of intellectual integrity on those using this material to bolster their position.

Update

Thanks to Andrew Moody for a link to another one. This time First Times in their November 2004 edition

Even the most cursory examination of Boswell’s documentation exposes the way he has struggled to force a group of documents to conform to his conclusions. Despite its facade of scholarship, the book is studded with unwarranted a priori assumptions, with arguments from silence, and with dubious, or in some cases outrageously false, translations of critical terms. And Boswell’s insouciance about historical accuracy would be unacceptable in an undergraduate paper.

…

All in all, then, this book does not begin to accomplish what it set out to do. (The reviews, after the early burst of hopeful publicity, have been notably skeptical-even from sources one would expect to be favorable.) Indeed, the author’s painfully strained effort to recruit Christian history in support of the homosexual cause that he favors is not only a failure, but an embarrassing one.