Well I have been putting this off because of Skyrim and Christmas so now that I have some free time I can finally write this review. Unfortunately not much has changed from the last game so go read that review and then come back here.
So the story picks up right after the last game. Desmond is now trapped inside the Animus and has to finish what he started with Ezio so that he can find out where to go next before the partition he's trapped in collapses. As for Ezio, he's out to uncover more information about Altair and his search has lead him Constantinople to find the keys to Altair's library and while he's searching he's helping the local Assassin's guild.
The game plays exactly like the last 2 games but now they've added bombs and bomb crafting to the equation. They also added a tower defence game for when your notoriety level gets too high but it's easy to avoid having to do them since you can just keep your notoriety level down. Other then these the only new things are a hook blade for riding zip lines and the new city. Seriously there isn't much new.
As for the multiplayer I didn't bother playing it since I don't care for multiplayer and it just a mediocre tacked on feature. I know there are new modes but I don't really care.
Like I said you can just read my Assassin's Creed Brotherhood review to read what I didn't write here. I just can't be stuffed writing the same review twice. Is it a good game? Yes. Is it better then the last one? Ehh about the same. Assassin's Creed is still a great game series but it's starting to show it's stuck in a rut. Maybe if we get a 2 year break, it might become fresh again.