The reason that I personally didn't like AC3 as much as say, AC1, 2 or Brotherhood, was that the main character was not in the least bit likable.
Connor, that is. Haytham was fucking awesome, and should they have made the game about him, I would have found it immensively more satisfying to play.
Connor walks around self-righteously murdering every person that are even remotely connected to templars or once exchanged a handshake with someone who at some point said something bad about "his people". That's all there is to it. He's unlikable, overly aggressive, vindictive, illogical and possibly some sort of supremacist.
This all came to a head near the ending (spoilers), when he spends a good part of the game attempting to murder Charles Lee, almost succeeding, tracking him to his home braving life-threatening injuries, and just straight up stabbing the dude in the chest who looked like he'd keel over from damage sustained earlier within the hour.
And for what? Because he was mean to Connor when he was like ten years old. He also stabbed his own father in the neck when he tried to stop him from murdering Lee.
Revelations had a problem like this, just not as bad. I never knew in Revelations why I was supporting Suleiman, one of the most brutal emperors in recorded history, why "Byzantine" seemed to be a synonym of "Templar", or why I even cared anymore. In AC3, the only constant is that Connor HATES templars, for no apparant reason other than that Achilles told him to.
Gameplay is allright, though.