Europa Universalis III might be the only game in history, bar any MMOs, which has received four expansion since it was released in 2007, at the pace of more than one per year, and has seen constant and important changes built into each of them by the developer at Paradox Interactive.
Divine Wind has just been released through the digital distribution service GamersGate and is especially significant to those who love a land war in Asia, bringing new mechanics, based around factions, to both China and Japan, making games with those powers more dynamic than before.
There are also pretty important changes made to trade, diplomacy and the building system that apply to the entire
Europa Universalis III experience and will probably lead old fans back to the game for another trek through history with their favorite powers.
My personal preference is to play Bohemia starting with the earlier 1399 date, when they are not too powerful but still part of the Holy Roman Empire, which brings a significant chunk of diplomatic and war based options to the game.
I played about 600 years worth of Divine Wind in several sessions and Divine Wind seems a good addition to the expansion family, although it does not have the impact which Heir to the Throne had with its Cassus Belli mechanics.
One change which I felt directly, apart from having to think more about where I trade and where I am to expand my Sphere of Influence, has been the new building code, which, because of costs associated and the fact that some province decisions have been turned into buildings options, made me approach the game somewhat more defensively, afraid to lose the money I invested in development because I did not defend adequately during a war.
Divine Wind also checks expansions powers somewhat because more allies can bond together to oppose one thanks to some tweaks to which countries can be called into conflicts, which is bad for the early game expansionist tendencies I tend to have.
We are also planning a full review for the Divine Wind expansion for Europa Universalis III: Divine Wind.