Will I like Assassin's Creed Black Flag if I liked...

...the Pirates of the Caribbean world in Kingdom Hearts 3?

I hear this comparison all the time. That world has pirate ship battles and a bunch of explorable islands, etc. People say it's like a knockoff Black Flag.

The Pirate shit is my favorite thing in any AC game out there.

Sadly, you need to spend a lot of time doing the traditional AC stuff too so it's hit or miss.