one strange thing is that it only appears to allow dx9 right now, and all the 2-8MSAA options are greyed out. the menu says dx10-11 is available with some sort of SP2?! very odd. many others are reporting this problem on the steam forums.
gameplay wise, the biggest difference is the hexagonal "squares" on the map. menus and production are much more streamlined and intuitive. animations are improved.