The main character, Adewalé, who also played a part in Blackflag is one of the most bad-ass characters I've played, not just in Assassin's Creed, but gaming as a whole. The is built like a tank, and won't take any crap from anybody. Proper bad ass.
The story is very DLC style length, and leaves you wanting more after you complete the main mission. There is still plenty of side quests, challenges and hidden treasures to find once you finish it, so for a standalone game, the quantity of gameplay is actually rather impressive.
Graphics wise, very impressive. Built on the same engine as Blackflag, you will not find your self disappointed at the visual side of this title.
I would highly recommend this game. If you are unsure about purchasing Blackflag, this is probably your best starting point as the gameplay is exactly the same, almost like a long demo. As a stand alone as well, this is a very well put together game that you will certainly get a lot of enjoyment out of.