I like period shows. I like them for the entertainment and I´m not looking for airtight historical accuracy. This is far from accurate but one can easily imagine it could have happened somewhat like this. In that regard it is believable writing under the specification of a TV show. Yet, I found this to be not quite as good as other historical fiction shows. Because it is hard to find sympathy for any of the characters. The way they are written makes it hard to like them, you could easily understand why everyone wants the Borgias dead and gone.
Technically there is nothing wrong with the show. Sets, costumes and the performance of the actors are great. Since they were probably surprised by the cancellation the shows ending is open with an unsolved plot. Whatever I think of the show it would have deserved a conclusive ending.