I'm a fan of AS games too, but I didn't play the AS Black Flag (did play all the AS games bofore it), because I only have a laptop with 15,6' screen right now and probably can't run the game on high. The same will happen with Unity, but I plan on buying a new PC as soon as possible. I'll give Unity a chance, because I wasn't dissapointed with any of the AC games this far. In my opinion, the game will deliver on its promises, because the know how to make a good game after releasing so many of them and getting the feedbacks of the players (I hope the do).