The Assassin's Creed series has a lot of problems if examined at all closely. The gameplay does tend to be very repetitive. The underlying "philosophy" is half-baked and peculiar. The story isn't particularly inventive. By the same token though, there are some very viscerally satisfying moments. The slow-motion drop from a rooftop onto a target doesn't get old. And one gets a distinct sensation of being the baddest man around from dropping into a crowd of a couple dozen guards and then walking away casually after piling up the bodies.
Because I'm a thrifty man (cheap), I don't buy the newest games as soon as they're out. I usually wait until a couple years have passed so I can get them for only a few dollars. So I'm just now playing through the Black Flag game even though it was released in 2013. I don't know that I want to play any more games, not just AC games, that don't involve me sailing around on my own pirate ship listening to my crew singing sea shanties. That, right there, is a game all by itself much like the Grand Theft Auto games where you can be reasonably happy just driving around listening to the "radio" that they have.