As Raz said, you know what you're getting. I still enjoy the series. You can''t compare it to CoD or sports games, it has a plot and a good one, it's not just copy and paste.
The Notre Dame cathedral took a developer 2 years to finish, one single building in the game. They put a hell of a work to make the city looks like it's RL counterpart, so that has to be said.
Plus I enjoyed the hell out of Black Flag and except for the bugs at release I'm enjoying Unity as well.