I suspect that more heads may have rolled at Canal+ Studios after this debacle, which must have cost a small fortune, than in the series itself -- and there were plenty there!
The Borgia story is certainly fascinating and this version pretty much sticks to facts, with certain liberties. The sets are sumptuous. The music is nicely appropriate, too (lovely 'a capella' choral music in the main). But that is where it ends.
The cast is a giant hodge-podge of European and American actors and, as other reviewers have stated, no attempt whatsoever was made towards any uniformity of accent. This, in itself, is not too much of a problem as everything is in English and there is just a general and generic European sound to their jabbering. But the high-flutin', and rather stilted, renaissance dialogue sounds even more so with emphases in the wrong places.
All this could be forgiven, but there is one huge, unforgivable, glaring exception that spoils what might have been a decent production: American John Doman in the leading, pivotal role of Rodgrigo Borgia. He may have been acceptable in his role as a NY cop (The Wire), but he is out of his depth here in every conceivable way. His acting is monochromatic and deplorable. His desey-dosey Bronx accent is shockingly out of place and distracting, and destroys whatever atmosphere the sets create. Unlike other reviewers, I could not get past this giant flaw because he continues throughout to top himself in lingual absurdity.
The cast is certainly attractive, but one can never believe beautiful Cesare's supposed 'conflict' between the physical and the spiritual in his life, nor just about any of his decisions, some of which border on the insane. Lucrezia is completely implausible for similar reasons. She, like other cast members, looks the part (if available portraits are accurate), but is just too 'innocent' to be believed. Certainly there is nothing in the histories to indicate that she was anything of the sort and, therefore, this is simply a 'dramatic' conceit on the part of the producers and writers. Juan Borgia is the worst of the lot, spiritually speaking: boor, megalomaniac (but they are all that), sociopath, sadist.
If the producers chose Doman as Rodrigo because of their pointed presentation of the Borgias as the original 'crime family' (and felt that his accent could bridge that association) then in that, at least, they succeeded. The family in this version are as unscrupulous, immoral, power-hungry, and thoroughly hypocritical group any ever presented on screen. Think of John Gatti 'worshiping' at St. Patrick's and hob-nobbing with Cardinal Spellman, after torturing and murdering two dozen people.
A colossal waste of time and resources. Doubly so because, with the same effort put into character development and sensible script as they put into physical resemblance, this series could have been quite wonderful.