Just finished it in two days, yeah definitely too short. But lot's of fun.
To those saying that they should've wrapped it up in this one, Ubisoft said from the beginning that this one is merely meant to wrap up Altair and Ezio's storyline, and resolve a few things from Desmond's storyline. So it's not like they conned us into buying this game, it is what they said it will be. And as a huge fan of the series, I'm very happy with how the two assassins' stories turned out, but feeling a bit disappointed about Desmond's. I don't see how they've shown us anything about what's really going on that fans of the franchise hadn't already figured out.
There are too many aspects of the main story that are either unresolved or unexplored for this story line to have ended with this game. I do hope AC3 is the last AC game, dragging it on any longer than that will kill this franchise IMO. I reckon the next game will not focus around the use of the Animus, aside from minor side missions.
In any case, Ubisoft had created two epic characters in Altair and Ezio and it only feels appropriate that they got a proper ending.
I did get confused about the mention of Cyprus at the end. Altair made a reference to it to his son so he can spread the rumor that that's where the apple is. The thing is that Borgia actually did find the apple there! I get that there are multiple apples, but why make a reference to Cyprus as if it was a fake destination when there WAS actually an apple there in AC2! Also, if Altair didn't put it in Cyprus, where did that apple come from? Need to do some digging.
By the way, am I the only one who was wary of Sofia at the end in the library? I was so afraid Ubisoft was gonna go cheesy on us and make Sofia a Templar all along and kill Ezio and take the apple.