I greatly prefer the former, however. I like the format—a 250 or so page book that describes a campaign, with enough detail to be easily usable, but more focused on bigger picture stuff than on "pixel-bitching" room after room after room. The latter is how I feel reading The Shackled City, however. Out of the Abyss feels very high level in some ways. Sure, there are actual text boxes here and there, and a few location maps, and NPCs with specific conversation details. But mostly, it describes the campaign at a much more high level, and expects that you as the GM will be filling in more of the details about conversations you have, NPCs you meet, and minor details of places you explore. It is structured to much more closely resemble a novel when all is said and done than your "typical" D&D adventure which would be incredibly boring as a novel as you explore every square inch of every room of improbably Byzantine locations.
Now, I suppose there are many GMs who, on reading that, would suggest that it seems difficult to run an adventure if you have to fill in many of the details yourself, and figure out exactly how to arrange the elements that it does give you. I understand that. I'm the kind of GM who prefers to do that anyway, though, so I find reading someone else's attempt to spell out every detail for me tedious and unhelpful, while an adventure that assumes I'm capable of doing so on my own filling in of details and instead gives me something interesting to work with that's flexible and high level is perfect. So... good for Wizards of the Coast for designing such a product, I suppose. Not that it's the first; apparently it's the third, even for 5th edition (in the wake of Princes of the Apocalypse and others, and even Third Edition Return to Castle Ravenloft seems like it has a similar format. I've flipped through but not read the latter, and I've read a few chapters of the former.)
So, the good news is that I've got plenty of more material to work through besides the more structured and detailed Paizo Adventure Paths, which is good. For one thing, it's already closer to a format that works for me, but for another, some of those topics are iconic and pretty interesting.
I had earlier said that I thought my own efforts to adapt Out of the Abyss were likely to see it moved to my comatose DREAMLANDS REMIXED setting, but I'm having some second thoughts. Where I earlier said that TIMISCHBURG probably didn't have a place for something as bizarre as even a heavily modified Underdark is likely to be, I'm now thinking that adopting an old idea from DARK•HERITAGE Mk. III where I had a gigantic Valles Marinaris (as on Mars) that was perpetually shrouded by a lowlying layer of cloud or fog. Underneath it was a bizarre world that bore only a few correspondences to the rest of the setting, because the environment was so different. And I think something not terribly unlike the Underdark combined with the Plane of Shadow can exist here, and may in fact be the true origin of the Cursed race (which here would probably take the place of the drow in the module. Roughly. Although I'm tempted to go full underground Sea of Omean and First Born here, especially since I'm re-reading The Gods of Mars as we speak.)
Anyway, I'm not going to do it right away, anyway, but it gives me a future project to work on, after I decide which of the two setting assumptions is more interesting to me; a gigantic canyon in the TIMISCHBURG setting (I've attached the old location bubble "map" and drawn in the canyon's probable location as a gigantic squiggly thing) or as it's own setting drawing heavily from Lovecraft's Dreamlands and Clark Ashton Smith's Hyperborea.
One obvious side effect of placing that there is that Gunaakt is, to a great degree, cut off from the rest of the continent. Tesculum is as well, although it can go around through Baal Hamazi and through the Lexoviian mountain ranges. But there's no denying that placing a gigantic rift valley that drops into the depths of the earth with difficult terrain and a persistent cloud cover is, for all intents and purposes, unpassable unless there are a handful of "passes" that are guarded and maintained as routes through them.