See, to me, this is one of the best things the product could have been.
I don't really need more brand new rulebooks, and I'm not playing in the AE setting. However, I'd very much love to see Ptolus and environs examined in detail--even though I'll never likely use the campaign as is. It's the same reason I purchased the core books for Morningstar/Forgotten Realms/Codex of Erde/Codex Arcanis/Legends of Excalibur, and a whole mess of others. I don't tend to play campaign settings "out of the box." The only campaigns I've run straight out of the "world book" are Eberron, Ravenloft, Scarred Lands, and (to an extent) Planescape. (And I'd be happy to do so with Dawnforge). Most of the time, I buy campaign settings in order to mine them for ideas, plots, entire locations, NPCs, and inspiration for my
own ideas.
The fact that Ptolus and the 3E rules were built around one another suggests, to me, that the setting and its options should have a lot of good ideas, and--even more importantly--present at least some amount of insight into why things are as they are, and how they could instead have been.
Monte, for what it's worth, I'm looking forward to this more than anything Malhavoc's done in a good long while.
(Though personally, I'm still waiting for a
Book of Countless Doorways II, as well.

)