Sequence 12 opens up back in Leonardo's shop and you are inspecting the newly acquired Apple.  It's too dangerous to keep it hidden in some random spot (like is has been for the last few hundred years) so you clearly must put it in a fortress with lots of people around it.  A visit to Forli and the Strong willed Caterina Sforza brings trouble in the way of a full on attack from a new target for Ezio.  Without going too in depth, this story played out well, had good cut scenes, and overall good gameplay.  My only complaint about it was that it felt very short (and no achievements).

Sequence 13, however, had me crying out expletives about every 2 minutes!  The Apple was taken and ends up back in Florence under the control of the Mad Monk, Girolamo Savonarola, who is using the Apple to influence the people to do his bidding.  In order to garnner discontent umong the people, Ezio needed to take out 9 of the Monks top people.  Normally I would think this was fine but about 5 of these were "Oh by the way don't alert the 80 bazzilion guards in the area when you do it".  I think I may have scared the dog a few times screaming at the TV.  God Bless the invention of the Sniper Rifle.  I think this one went on a tad long (maybe to make up for 12 being short) and could have done fine with maybe 5 Assassinations instead of 9. Also....Needs Achievements!

Overall I was very happy with the story except that it all should have been in the game to begin with.  It's not like a new story, or a special side mission.  This was all info that was a part of the main story!  So why not include it in the main game.  I also found the DLC to be a tad glitchy.  There were many times where the Dialogue was not heard at all and just the subtitles were what I had to follow along with.  After one mission I was spawned inside a building and couldn't get out without having to quit.  That mixed with the standard frustration of alerting guards and failing out of a mission about 50 times really made this part of AC2 more of a Chore than enjoying the added story.

My Advice?  Download the DLC THEN play the game so it's all one coherent story.  Where I gave the Main game an 8.8 out of 10 Florins, The DLC is getting only a 6.5.