One of the aspects I like most about the campaign is the structure. The players get to a certain point early on at which the whole world opens up as a setting for play. It is revealed that the cultists the player-characters have just tackled in New York are not alone, and there are allied cults all over the world working together to bring Nyarlathotep to Earth.
There is a time limit, but otherwise the player-characters can take on the various cults in any order. Although the campaign feels epic, it doesn't do it through imposing a strict narrative order.
We've been playing Paizo's Carrion Crown
To be fair, Pathfinder campaigns do not seem to feature the most flexible narratives, even when they are accompanied by the trappings of a sandbox, so it's no real surprise that Carrion Crown didn't open up in a similar way to Masks, but it is still disappointing, because finding a map with "Go here next!" on it in big red letters -- I exaggerate, but not much -- only draws attention to the linear nature of the plot.
The Pathfinder campaigns are released in monthly instalments, but that shouldn't prevent a more open structure to a Masksified Carrion Crown. I doubt many people play the things as they are released, and besides, Paizo could have chosen a publication order without imposing a narrative order; Masks of Nyarlathotep is a physical book and is by physical necessity presented in a certain sequence, but it doesn't have to be played in that sequence.
Perhaps a more open structure would have been difficult to meld to Pathfinder's level-one-to-level-twenty power progression, a mechanical issue about which Call of Cthulhu doesn't have to worry; tackling Nyarlathotep in Shanghai is just as difficult as fighting him in Cairo in Chaosium's system, but Pathinder characters in the same situation might find themselves too powerful as a result of their experiences in one location to find much of a challenge in another. All that said, D&D players have been running open sandbox games with the same kind of progression for decades and Paizo should be able to figure out how the maths of their own core system work.
Carrion Crown is fun to play, by far the best of Pazio's offerings we've played so far, but I can't help but imagine how much better would it have been if they had pinched the structure of Masks of Nyarlathotep. The latter campaign may be almost thirty years old now, but it seems it can still teach the game designers of today a thing or two.