For those that remember this far back, the Pathfinder Gazetteer is very much like the Old Grey Boxed set of the original 1st edition Forgotten Realms setting. It gives a quick overview of many places within the Pathfinder campaign setting, enough to get a feel for the world and how the various nations interact.
It doesn't go into great detail in any one place, but it does cover a huge amount of territory, and introduces a wide range of deities for the setting and various lands for various campaign themes. Its great for a quick overview and some sound bites about the setting, and it doesn't seem like it gives away too many secrets that players running characters in the setting would have a problem with.
One problem, which isn't exactly with the product per se, is that the Campaign Setting book, which is much more detailed, is already available. However, this book is still a great resource for players that only need an overview of the setting, or even GMs that only want the bare minimum in a campaign setting and don't really want to get too invested in one, other than to have some context for their campaigns.