I dabbled with the demo this morning. EUII's engine in high res actually looks very decent, and it's a blessing for the eyeballs to have the game running in the correct resolution for my LCD monitor. Text is a bit on the small side though. The map scrolls correctly too; I always used to have problems with hitches and tearing with the vanilla EUII map.

If there's one thing I learned from this demo it's that I have forgotten everything I used to know about how to play EUII! I went in search of a manual and found a 156 page long mammoth tome that one of the designers has written. It covers everything in exhausting detail and may actually be the most (only?) useful manual for a Paradox game thus far. A fast scan of it reveals that there's quite a bit of neat stuff in there.

The UI tweaks and changes appear to have helped a lot. It feels much more user friendly than I remember of EUII.

Music is all taken from EU3. No more Falalalan.

So it appears that the answer as to why anyone would want to buy an ultra-tweaked, modified and lightly modernised version of EUII is that it's an ultra-tweaked, modified and lightly modernised version of EUII.