Great on big picture, but there are a few things that could use some work; them later. It is great to see the Prestige classes (Harrower, Hellknight, Low Templar and Red Mantis Assassin) from the Chronicles redone. The new Inner Sea feats are nice as well as the details of the Inner Sea factions. The racial breakdown is also very nice which includes regional "hot spots" for some races also - "Hey look mom a Shoanti section!", very cool. Also a cool bonus - what the Holidays are and how they are held/celebrated.
The overview of each country is also very nice with one small issue; why didn't you cover areas on a map that are labeled?!?!?!? Example: Andoran pg. 44 11 locations are lightly covered by the Gazetteer while 30+ are displayed on the map. It would make sense to me if you just covered cities/towns, rivers, forests or ruins; you did not. There is a mix of cities, forests and ruins. The other locations are not covered, some are covered in the Adoran Companion, but there are a number of areas not covered at all. This is just Andoran, not to mention other regions that you cover - Varisa, Karapesh, Osirion, Cheliax, etc. These areas make the Inner Sea World Guide fall short even when adding in area Companions to cover what its name implies Guide for Inner Sea which would be to include named points on a map in said guide.