From my point of view, the most noticeable changes will be my minimods ;-)
So more reasonalbe acquiring of traits, more reasonable traits, better provincial offices, and ministerial offices as well (there're descriptions for these).
Hopefully, the loyalty system would work better. Also the fog-of-war should be more visible (you've got to build the watchtowers by yourself, and it's going to be costly, all characters have shorter line-of-sight as well).
So from this point of view, if you happen to play the game, I'd advise playing Poland. If you do,
you may find this article interesting ;-)
One warning: the modifications for the crowns has not been made so the description which will appear at some point is not really true - the crown system is still as it was in 092.