Phew! This is not an easy read! Meyer may have set out to write a book about the Borgias, but what he's really produced is a geopolitical overview of the Italian city/states and Europe during what you might call the "Borgia years" - mid 1400s to early 1500s. The argument certainly can be made that detailed, elaborate context is required to fully understand and accurately interpret the evidence related to the Borgias. Even so, I feel like the author went WAY beyond the stated scope of his project; whole sections of this dense work barely even mention the Borgias.
Having said that, I appreciated the opportunity to learn more about this fascinating epoch in human history, which has much to teach us about the senseless, futile butchery and misery that results when people devote themselves exclusively to the pursuit of wealth and power. This has always been the rap against the Borgias, of course; that in an age characterized by grotesque excesses of violence, passion, and ambition, they played the game more ruthlessly - and more successfully - than any of the other great families ...
... or did they? Meyer does a fairly creditable job of presenting the "evidence" against the Borgias (much of which, tainted as it is by hearsay and bias, would never be accepted as "evidence" now), placing the evidence in context, and making the case that the Borgias have been much maligned. Sure (he argues), the Borgia popes may have engaged in gross nepotism, but a case can be made that they were competent administrators who advanced by virtue of luck and ability rather than mass poisoning; Cesare may have justly served as the model for Machievelli's The Prince, but he wasn't noticeably more brutal or amoral than his peers; and poor Lucrezia may have gone through three husbands, but there's no actual evidence supporting the allegations that she was an amoral temptress who actively plotted their deaths.
Given the dearth of historical records, and the distortions contained in the documents that have survived (history is written by the winners, it is justly said), I'm not sure there's any way now to know where the truth lies; all I will say is that Meyer manages to make a fairly convincing case that a critical reassessment of accepted wisdom may be justified.
In summary, there's much here to recommend. The topic is worthwhile, Meyer certainly knows his period, and he does a creditable job of shaping the convoluted material into a form that's relatively accessible and interesting. However, I'm not sure other readers are going to be as tolerant of his geopolitical digressions as I was, and the denseness of the subject matter requires an application of concentration that some may be unwilling to expend.