Maybe I'm just consumed with Game of Thrones, but I didn't care much for this season. Things just seemed to happen randomly without any explanation, most of the characters were never fleshed out. della Rovere and the other cardinal that burned the papers just disappeared.
Some plots seemed incredibly rushed. For example, the new king of Naples that was plotting with Caterina Sforza, we see who he is at the end of the episode, Lucrezia finds out the next episode, and 5 min into the following episode she escapes.
The group of second/bastard sons was pointless. Caterina recruits them, Cesare meets with them and they basically just agree to change sides without any hesitation. I wouldn't know most of their names if I didn't have closed captions on. They hint at a Rufio/Micheletto showdown, but that never happens. Micheletto disappears until the finale where he serves as the deus ex machina to help Cesare siege Forli (ironic since Caterina mentions a deus ex machina).