I have mixed feelings after reading this adventure.
There are some things to enjoy about it. I definitely want to see more high level adventures (and Adventure Paths specifically), and I love that the adventure acknowledges that high level PCs will have options that might trivialize some encounters, such as being able to fly or speak to dead characters. I like the demiplane home base for the PC's and the fact that they get to spend some time in Absalom. I like the philisophical question at the heart of the AP, even though it doesn't get many words dedicated to it in the actual adventure.
Now to the bad. First off, the PDF is a staggering 196MB for some arcane reason. The map pack is missing the end-of-module dungeon from the back of the book. Usually Paizo is much better about this sort of structural work and it's a bit disappointing to see errors like these.
But to speak to the adventure content, I'm also disappointed here. Fanservice is a knife that cuts both ways, unfortunately, and while I know that I as a GM have enough Golarion lore knowledge that the significance of seeing some of these locations is interesting... I know for a fact my players will not notice or care. References to old adventure paths and modules are going to be meaningless to the vast majority of players.
I'm not a fan of teleporting into a location for a single encounter and then disappearing to never speak of it again. There's a lot of places where the adventure just says "regardless of what the players do, [X] attacks shortly." It makes every location feel meaningless, with only the lore novelty to string it together. The Harrow theming is interesting but not even I (the resident lore buff of the group) have bothered to memorize the symbology of the entire fictional deck.
I'm especially disturbed by the sidebar that recommends teleporting your players back to the plot if they jump the rails (!!!).
Overall if I ran this I would do heavy rewriting to allow more player agency.
