For instance, my beloved World of Greyhawk has gone through many different published iterations. The original folio is still considered to be a masterpiece of almost Hemingwayesque brevity. A few pages of the broad outline of history, a paragraph or two of description for each nation (with a few notable exceptions), and a line or two for most geographical features. That 32 page folio book and those two gorgeous poster maps by the talented Darlene were all there was. A minimum of detail, and those maps to inspire the DM to fill in the details through his own creativity.
By today's standards, I daresay it would be considered totally inadequate. A setting without mention of religion? No lists of NPCs? No adventure hooks? No diagrams of castles and maps of cities and regions? Unthinkable!
The gold box followed, with the same maps but adding a lot more detail, including weather, deities, encounter tables, and more. Then From the Ashes, which advanced the timeline, and included mini-adventures, And so forth. Each edition of Greyhawk filled in more and more detail.
The Wilderlands setting (which I knew at the time as the City-State campaign) from Judges Guild was almost the opposite. It was focused on the small-scale, and piecing together the shape, powers, and events of the bigger world from the smaller pieces was, to me, a difficult thing. I still loved it, though.
My question is, though, what strikes you as the correct balance of detail and vagueness (for the DM to fill in himself)? Personally, I get turned off by settings that pile on tons and tons of obscure detail, to the point where only obsessive-compulsives and those without jobs or families to distract from reading everything that is published for the setting, can keep up. Forgotten Realms, I'm looking at you.
Which is not to say that the FR doesn't have its high points. The grey box was a masterpiece, managing to be both detailed and inspiring in a single stroke. But then the inexorable torrent of supplements and novels came at us like the undamed river Angren coming at Isengard. And to be fair, a lot of people really like that level of detail, knowing that wherever their players journey, the DM can just pick up the appropriate supplement off his shelf and have at it.
So what's your detail-vs-vagueness sweet spot for settings? Are there features you look for? Things that turn you off? Must-haves?