How much quality a product has means nothing if one doesn't actually like what the product does. I've read enough reviews about RPG products to know that I could have absolutely no use for what the product describes, not wanting it in any way, but someone else will still go on about how great it is. Someone saying how great a product is meaningless if that's all they do. It leaves those of us in the dark about what the product actually contains having no context for their "greatness" speech.
And that's all the people who've written reviews about Pathfinder do: say that the product is great. It could be "Exact Generic D&D Fantasy Clone #3278" and I wouldn't know. I need to know what's in it, and be told in such a way that I can understand what parts are causing people to single it out in comparison to similar settings.
Perhaps this would be a little easier if you told us what you liked?
Let me tell what i have gathered from the PF campaign setting book.
1. It is broken down by region, and most of those regions are unique enough to be good seeds for campaigns in and of them selves. As far as variety of theme on the regions? There are some that seem to be homages to various themes and places found in the old D&D campaigns themselves, to popular themes in fiction and fantasy themselves, to completely original concepts. And to be fair, even the regions that feel like an homage still have a good bit of original and quality flavor to them.
This modular nature makes the setting great for insertion into whatever fantasy gaming system you are into. And it has been my experience thus far that the quality of writing found in the books, and the presentation of the fluff make them excellent reads in and of themselves.
2. The setting has pretty good support in the terms of modules and small optional materials. There are map folios, stand alone adventures, fluff books on cities, sites, and monsters. It has its own pantheon, and planar cosmology. In fact there are many aspects of the setting itself that are fairly detailed, but not so much in way that says: "You have to tell this kind of story". Rather I find that most of the material is rather open and supportive of telling your own story. Its kind of a framework. A lovingly detailed framework, but a framework none the less. There are no real uber NPCs that drive the story. All of the material is kind of offered with the idea that the players and DM drive the story. Even the modules and such offer ideas how to get off the beaten trail, and usually offer tips for what to do if the players kill a story NPC to help them find their next objective.
3. It is still in print. You will not have to pay collector prices for it. You will be able to get it for cover price or less. It also is supported by a pretty decent community, and a company who seems to interact with that fanbase fairly regularly.
But all in all I would imagine there is a place in Golarion for you to tell the stories you want to tell. Because most of the places and neat stuff in the setting isn't detailed down to a razor's edge (there is plenty of detail offered, but its not usually presented in such a manor that feels counterproductive to original stories) it leaves a lot of room for creative storytelling and original storytelling for your groups.
In some of the classic settings for D&D it often seemed as though the characters were on the sidelines and the real story was about the history of the setting and its major NPCs, and unless you stray far from what is presented it often can feel like the players are the supporting cast for the settings story (though this is not always the case).
The way Golarion is presented, it is interesting enough to catch the interest of the players and often be exotic (for example the very first module of the very first AP supporting Golarion has the group adventuring inside of a gigantic stone head left over from some ancient civilization. It was enough for my players to all be very interested in the site. But the ancient civilization itself, aside from a few specifics needed for the module, was not very detailed, so I could kind of mold them into whatever fit the mood of my story the best), but not so detailed that there is no room for a DM to change elements of the setting. No place or NPC is crucial to the setting to a point where tinkering with them effects the whole place.
In short Golarion offers everything. Paizo's fans pretty much decide what the course of the setting is, through interaction with the developers, and community participation. There is no unique theme that defines the setting, but do to how it is presented in a modular fashion there is no reason why you could not add overarching themes to the setting without having to basically recreate it from scratch. It functions as a canvas that stays firmly in the background, but is interesting enough make the story more alive.
love,
malkav