Soo.. yeah i played Sengoku, also i am a total Japan nerd. I love Japan and the Samurai culture, although i have to say that the game disappointed me. It isnt complex at all. I play paradox games because i love long, complex games where i have to manage a lot and can manage an enourmus amount of different things.
Dont get me wrong, the money i spent in the game was ok. And i also had fun, but its not a game i can play again and again and again. The Map for example is way too small, i dont mean that its bad that its only japan, but i think that even japan is too small. I dont know, it could have been so much better. This game was worth about 40 Euro, although Ck II, Hoi3 and Vic2 are worth more than 100 Euro (in my eyes).
So i would say this game really needs expansions, better probably an entire rework. Dont get me wrong, probably some thinking something totally different but i think Sengoku would have been much better, if Paradox would have just taken CKII and configure it for the Japan setting. Although it would have been much more interesting, if there would have been china, Korea and Japan.
Something i would also look forward to would be a game whish makes it possible to play european and asian dynasties at the same time (in the medieval or antic age). Imagine the Chinese never destroyed their fleet and went to europe... colonizing it.
In EU3 its a bit too late for that (i think).