Renter not a buyer.
Free-running through the environments feels smooth and enjoyable, hunting is fun and exciting, and the cities are large and take a decent amount of time to explore. Collision detection could use an overhaul, as the game experiences environmental glitches quite often.
Sea missions provide a good break from the normal quests and were well mapped out.
The music is pretty good and provides a sense of immersion, but after a while you want to stop hearing the native drum beat in the background.
It is much harder to sneak up on your prey, but not in a good way. Sometimes enemies detect you for seemingly no reason, and this tends to frustrate after you have planned out a method of attack.
All in all it was fun, but I would rent it before you purchase it. I haven't tried the multiplayer, nor have I completed even a fraction of the side quests and this may be a game changer. All I can say is that I beat the main story in a weekend. Good writing, though... I'll give them that!