In the last two nights, I have successfully retrieved the Apple of Eden and vanquished the darkness that threatened Albion. Oh yes. I've been busy.
Besides rebuilding Rome and doing your usual treasure/flag/feather hunting (the latter two show up on maps now, which is SO MUCH EASIER), you also get to train assassin recruits and build your brotherhood. Honestly, I spent hours just sending my peeps out on missions. You can also call them into battle with you (I lost two good assassins that way *sniff*) to help when you're overwhelmed with guards. And trust me, they are indispensable assets.