For the Assassins Creed saga, Black Flag gives things a change up, and that is a good thing. The combat is pretty much the same, with counters and disarms, but the overall lasting effect is it's take on exploration. Finding new areas and capturing all the small things in this game is a lot of fun and can be very addicting. This game encourages exploration by having beneficial collectibles throughout the game for crafting and or monetary rewards.
Aside from discovery, the overall story of this game was amazing. YOU MUST BE CAUGHT UP BEFORE YOU PLAY, and if not at least play Assassins Creed 3 first. This game provides an epic story that gives a lot of information that is vital for the overall modern/futuristic story which is epic.
The little things throughout the game are amazing. The idea of crafting has been thought out, the main ship in this game can be upgraded from the Cannons to the Hull, and your Crew can learn songs to sing in the ocean seas while traveling.
While all of these things make Assassins Creed great there is a downfall which to me is the multi player, which is a giant: Meh. Until Unity comes out, which will provide a Co-op Story, the multiplayer in this Assassins Creed and previous ones are for moot and provide little enjoyment. The Multi-Player for me is the reason why this game did not receive a perfect 10, if it was a stand-alone single player experience I would have given it a 10.