EU3 only gets better.
Now I'm going to focus on the expantion itself, so to get more info on the core game you might wana look that up:
First I must say I'm happy they gave us a longer game timeline, the fact that I can go back and play nations that had already been destroyed was great. I often found myself playing Morea or Tebizon to try and rebuild the empire but thanks to the new expantion I actualy get to play the empire!
With that said I'll move into another great area... rebels. In the past they just poped up and created chaos for anyone and everone, no longer! Now rebels have a mission, a purpose and they relentlessly go after it. The game now supports a wide range of rebels from Peasents, Freedom Figthers (destroyed nations trying to make a comeback), Patriots (rebels trying to rejoin a nation that lost land) and even religious zelots! The rebels will restock armies and they wont leave the contry they're rebelling against. So if your playing Ragusa Serbian rebels won't attack you once they're done with Serbia, rather they camp out in Serbia till the issue is resolved.
Aside from the expanded rebels you've also got nation missions, if your playing the Byzantine Empire for instance you'll have the mission to recapture Greece, then Asia minor. If you're playing Naples you get missions like gaining prestige. The missions are fun, and you can even pick your mission to a dagree which is realy nice, completing them gives you a fair bonus depending on what the mission requires (some are to form up ethnic nations like "Germany" or "Russia" even "Italy" joins the list).
Along with the great new features EU3:IN adds a ton of fixes, the auto send merchant option has been fixed to the point where it actualy works... yes I've actualy dominated three trade markets without even bothering to pay attention to them.
As always EU3 continues to deliver the best "grand" conquest experience allowing you to play any nation in the world at the time. I stand by it that EU3 is currently the best "High Stratagy" game I've played yet and this expantion only continues to polish an already sparkling gem.