I am a fan of Tim Hitchcock's work and have been looking forward to this.
I think the hook: 'Rescue the hero!" is fine, and not one I've seen before in a Paizo module.
Starting with a non-violent, mini-sandbox involving a slave auction is cool but not for every group.
The dungeon is full of variety and everyone is someone to interrogate. However, the tunnels do have a bit of an old-school random monster population (otyughs, mimic, black pudding, rust monsters, cockatrice, minotaur) and add to the old-school sense of random lethal-ness by being chock full of traps.
Pesh addicts and Pugwampi add to the katapeshi vibe and everyone loves slaying gnoll slavers.
The slow reveal on the Lamashtan cult is nicely done, clues are smattered and will build up a picture over the adventure. The pace of the reveal depending on how alert players are and how many clues they get with skill checks and the like.
But... this is then spoiled by Othine's reveal: the PC's investigations are only foreshadowing for her reveal.
The cult compound is nicely demonic (you immediatel hit upon quasits, minor demons and krenshars). The morlock and howler, though, again feel like random monsters. The traps, rooms and cultists are excellent (graven guardians, voice of lamashtu) but the mid-way BEG, The Midwife, is a bit of a mess (half-fiend jackalwere oracle, anyone? No, thought not). The obvious alternative would have been a flind, or a gnoll with more levels. Even a half-fiend gnoll would have been more fitting.
The black milk mother is horrendous but is a captive and could have been more intriguingly pitiable. She gives birth to advanced hyenas each month but there are no advanced hyenas on the adventure!
Ukrammak should be a party ally (to destroy the ghost) and then Ukrammak and Uthine should both turn on the party: that would better that leaving a ghost-destroying-kit in Ukrammak's quarters frot he adventurers to find.
My thoughts: not a bad adventure but the random monster selection should have been replaced by more cultists, slavers, gnolls, hyenas, flinds and Yaenit Demons.
There are hints of Hitchcock's talent poking through but this feels awkward and ultimately disatisfying.