The Medici Secret (Michael White)
I expected this book to be terrible. I was right! I gave it two stars ("it was ok") on the grounds that I remained interested enough to keep reading, though this wasn't the author's fault -- Cosimo and Contessina de' Medici were the people that kept me interested. The non-historical characters included were 2D, the romance was so completely undeveloped it just made me laugh, and the whole thing just seemed way too melodramatic. The jumps about in time (and space) were irritating: novels don't have to be linear, but I'd rather there was some kind of rhyme or reason to it. In the first few chapters alone we go from 1996 to the present day to 1410.