The perfect world map script works just fine, I can confirm that much.
Though every now and again I'll load into a game with nothing on the map and insta-lose, but that's rare, and everything else is just fine.
Edit: though I do remember seeing a thread somewhere about a map script that had problems with AI not colonizing the new world with BNW, so maybe there can be issues, but I didn't read it, so I don't even know if it was valid, and I certainly haven't noticed any problems using Perfect World 3.