Bloody hell, I haven't even finished AC2 yet! I got to the bit where the world pretty much opened up and I rather suddenly lost interest. I mean I had fully upgraded my little town, I'm pretty sure I had every weapon (only one of which I ever used) and I just got the impression that a massive grindfest was just lurking over the horizon ready to make me really have to suffer to get more story.
...plus of course Mass Effect 3 came out about that time.