Played some of the demo. Played as Portugal until 1520 and did the 3 tutorials.
As always, the tutorials are not that good. It basically tells you where to find the menu's, but doesn't tell you what they're good for. The game has changed dramatically compared to EU III. You can no longer mint coins, economy and technology are separated. Instead you get 3 new resources to manage your technology ("monarch points"). Each nation now also gets a bag of unique historical ideas that are unlocked as you progress (for instance for Portugal this is the legacy of Henry the navigator, giving +20% colonial range).
Annual incomes are gone, you only get monthly ones. Since minting is no longer an option, your finances become more obscure. They are now depended on your trade and taxation, both things where you have limited influence over. Expanding your realm has become harder, you now get a penalty for over stretching your empire. On the other hand, converting, gaining cores and changing culture has become allot easier then in EU III
All in all, it seems that it will be allot harder to get your nation on the map starting as a minor. Gone are the days of mass minting, recruiting 10k or so mercenaries, just to annex your one province neighbour. Since it's harder to accumulate cash, I believe your options will be very limited. Anyway we'll see when the game is released (which is actually Wednesday in Europe, not Thursday as I said )