Gameplay identical to Black Flag but despite that it manages to add some novelty to it. The story is also very good and manages to tie the kenway trilogy together, and also as a bonus it connects it with AC Unity with the ending.
The world is very big (about as big as Black Flag) but set in a colder biome with many unique locations with treasures and collectibles all over the map, making it very interesting for completionists. Naval Missions are horrible.