I don't have the iOS 6 beta, but it uses openstreetmap and I live in zambia, which is a very small country. Openstreetmap is pretty darn good for street level access, even more accurate than google maps. I have no idea about 3d.
3D is worldwide, but you only get 3d BUILDINGS (flyover) in selected cities. The rest of the world gets satelite nav pictures mapped to a 3D terrain ala Google Earth.
----------
If you are using multiple languages (keyboards) the dictionary now collates all the languages into one dictionary regardless of which keyboard you are using. Handy for bi-linguists like me who don't always want to jump to a different keyboard just to quickly reply to a message in my second language.
Also there's a separate Australian keyboard/dictionary now. Yay!