The Storie is less compelling and the innovations are boring and really unnecessary
example
The Hack blade - had completely unnecessary because Ezio learned the climbing jump in Part Two
Defend fortresses - I have to say something else ??
I've just bought the story of Ezio to finish my game. While the rest of the game puts again to voltage but can not tear the rudder around.
All in all, only weak average still important if you want to experience the story to end.