Compared to the update I mean.
i would say not getting it would be a mistake. You would be missing Marches, AI control for wars, peace options, new casus belli options, unit builder, fleet maint. options, fleet AI control, nearly 100 new events, literally all of the 30 years war content, and lastly all the client state and revolution stuff.
Also, huge update, all your previous saved games are forever fucked. The whole map looks like swiss cheese when you try and load up an old game since they added all this new land, the old save file just makes them all terra incognita.
Im also super glad to see that National Ideas have been pretty much squashed, only like 5 countries now have National ideas. Another thing i noticed is that Albania no longer starts at war with the Ottomans and they have their own idea group, Albanian. England and France also do not start in the 100 years war any longer.
Africa has also changed a ton, the entire western coast of Africa is now Wasteland, so Portugal and Spain are going to be neck and neck for Colony supremacy, while France and England will be an afterthought. Though while i say that, there is something like 700 new provinces so there is plenty of room for all.
In a way it kind of saddens me, i knew so much about the game and how one should start with most of the countries to get a good start. You can toss all those old guides right out the window now.