Okay so I am not a huge Assassin's Creed fan. I loved the first, didn't get into the second, haven't bought one since. Additionally, I disagree with the fact that one comes out every year and strives off of shirts and a ridiculous amount of merchandise that people who don't even play the game buy.
HOWEVER
Hell_Shadow let me borrow Assassin's Creed Black Flag, and because my PS3 broke and there is nothing else on the ps4 to play at the moment besides warframe which he and I played constantly for weeks now, I've been playing me some black flag.
And I must say, it's really freaking fun. I don't know if it's really that good of a game, but I know that it's fun. Really fun. There's so much to do in that game that it's ridiculous, but it's balanced really well. By the time you get bored sailing around, you're on an island assassinating people, and by the time you're bored with that you're in some giant pirate sword fight, and by the time you're bored with that you're playing some weird ass pirate battle simulator, and by the time you're bored with that you're outside of your animus talking to your dickhead boss. And at any time if you're bored with any of that, you can just explore. Find treasures and booty. Mostly booty.
So if you like Assassin's Creed at all, I would say buy this game, but idk it barely resembles Assassin's Creed so actually if you like Assassin's Creed and pirates and ship battling simulators, this is the game for you.