Just finished the game, hugely disappointing. I won't re-iterate my gameplay complaints from before, but aside from that they do jack fucking shit to give the game any sort of focus, story, or characters that you give two shits about whatsoever. People are introduced and die but you don't care, and there's no sort of focus or "villian" until arguably the end, and that's it. The sense of progression in this game is totally messed up; I probably spent literally 3-4 times in this game doing side stuff not related to the main game, and if you did just the story missions you could probably beat the game in a sitting, it's super short (despite the number of sequences it throws at you). The Desmond bits were sort of interesting, but also didn't really add anything. The game's title is completely misleading, someone could fill you in on the events of this game in less than 30 seconds before playing the last game, it's complete and utter filler. It's still a good game on paper mechanics-wise (at least once you lock all your dens, and if you completely ignore Mediterranean Defense) but everything else is not great. Definitely a 7 or 8 at best, and I would have rated the last two games 9.5-10.
Also as a complete aside, it is super disappointing that when you call your assassin's out, they no longer say cool shit before they run off like they used to in Brotherhood (like "Death is the fate of all men", etc).