Golarion's biggest strength is that it is more or less a generic 3rd edition D&D setting. They basically made a list of any kind of adventure a D&D player could want to have and made a place for it. There's an Egyptian setting, a jungle setting, a place where a sci-fi spaceship has crashed, devil-worshipping nations, Arabian Nights, black powder using peoples, frontier lands, Viking lands, major metropolises, three flavors of Underdark, etc. etc.
And somehow they manage to do this without it coming across as a complete hodge-podge like some D&D settings I could name.
Where it really shines is there ability to look at old tropes and make them fresh, an approach they've taken to making old standbys like goblins, ogres, the fey, and ghouls really scary again. They even have an upcoming book where they take a look at popular magic items and I look forward to seeing how they can make a bag of holding fun.
If it suffers from anything it's that the creators like too much fantasy literature. Thanks to their love of mythology (both ancient and contemporary), they've been tossing in everything from arcanotech to H.P. Lovecraft. They've got aliens from space, dinosaurs from the lost lands, and urban legends from right next door. You could seriously encounter a Hound of Tindalos just minutes after fighting off a pack of chupacabra.
