This game deserves game of the year. I do however have some complaints that I don't see anyone else voicing, so just because my list is detailed, that doesn't mean I don't absolutely love this game.
1. You don't get to come out of the Animus enough. I really missed regularly coming out of the past and seeing how things in the present were shaping up. It would have been particularly cool in this game. They did however justify this logically in game, and when you did come out of the Animus, it was some of the best moments in the game. So while I miss coming out more, it was done right.
2. Lucy looks completely different. I don't know why. They even show a clip of her at the beginning. Then she comes in your room and she is just different looking. Desmond also looks a little off.
3. The glyph puzzles towards the end defy logic. Don't get me wrong. I love a good puzzle. In fact, solving the glyphs was a great aspect of the game. The problem was when you would come up with a perfect solution and then have it not work. Then even worse, when you use the hint option, the guy tells you what you have come to by yourself should work. But it doesn't. So you have to go online, and you get the answer and its gibberish. My answer that didn't work was way better than the actual answer twice. I think they wanted to sell guides or something.
4. The time transitions in the game were not really felt. Ezio never looked any older. After one transition he did grow a beard, but that was it. I would have like to see or at least get a clue that some time had gone by and what Ezio had been doing during these years.