Great new gameplay ideas offset by a loss of historical flavor
EU3 has some great new gameplay ideas, such as national ideas, military tradition affecting your ability to recruit generals and admirals, and recruiting regiments that slowly are reinforced after taking losses rather than recruiting individual soldiers.
But unfortunately, for some reason they decided to completely destroy the historical ambiance of the game. The graphics are just plain ugly and a big step down from the beautiful hand drawn 2D map of the previous game (with the added bonus of people with older systems not being able to play it!), the music is boring, cookie cutter, cinematic music rather than the great period music selection that changed as you advanced through ages in the previous game (because playing as the kingdom of France, nothing gets me pumped up for war against Austria like a jangly Middle Eastern-sounding track) but by far the biggest loss is their decision to do away with the historical events and leaders that really gave you a sense of reliving history. I haven't quite decided yet if the new ideas are worth the loss of ambiance. I'll play EU3 some more and I may decided that it is an improved, if flawed and highly disappointing, sequel. But I wouldn't be surprised if I eventually decide to resign EU3 to the dustbin and go back to EU2.