So if you're reading this, I'm going to assume you're (A) interested in running stand alone modules for mid-level Pathfinder groups and (B) looking for good modules to run.
(If that's not you, check out my post on Maggot Lamias if you're into D&D 5th Edition and you don't mind some artistic nudity, or maybe this other thing about killing your friends in RPGs.)
With D&D 3.0/3.5/early Pathfinder modules, monsters tend to be far too frail. Power creep is real. My advice is not to fight it by nerfing players, but to simply double all the hit points for your monsters. The Hunter can throw down 100 points of damage on a turn, easily, and the Paladin averages 30 per hit, occasionally reaching 100+ on Critical Smite Evils. If I want to challenge them, I need to keep my monsters around for more than a single turn.
For this mod specifically, I rounded the Doomguides up from 44 to 50 hp, and made the hydra/dragon lake monster a Colossal monster with triple hit points. It made sense to me to keep the fodder monsters weak and make the boss monsters beefier. This made the Manyfaced One a scary fight, but I'm glad I did it.
|These evil dwarf valkyries are metal as fuck. (Artist Unknown)|
Abadox. At some point, the dungeon itself animates and becomes a monster, with the players trapped inside. How cool is that?
Tough Fights. The Manyfaced One deals 1d4 ability damage to a character's LOWEST stat! He also deals ability damage when he "reveals his true form," 1d4 to each of STR/DEX/WIS unless you make a saving throw. Brutal. A follow-up fight with a pair of Spectres had my players justifiably panicked.
Intriguing. The political intrigue in the first section of the adventure is actually a lot of fun to roleplay. It's a little useless as-is: It'd be nice to have some noblemen listed in the dwarf king's hold, but I suppose Pathfinder Society is more about "Ok, read them this text block, have them select YES or NO, then read the following text block depending on what they said." Ok, that sounds like a complaint (and it is, but about PFS, not this mod specifically), but I enjoyed the introduction and my players enjoyed bantering with nobledwarves.
You commit regicide. How fun is that? As a DM, you need to be prepped to deal with whatever happens next for Glimmerhold once the king is dead, but that's good material for future games.
It's verbose. You'll need to make a couple crib sheets in order to get through this module without constantly re-reading stuff or looking up monster abilities.
Interesting yet pointless backstory. Yes, the betrayal of the dwarf king fuels the main conflict, but the players go to the monastery because "The King commands it!" The Mistbreather Clan, the Rovagug giants, a hundred years of history and intrigue, it's all just so peripheral. My players never figured out the "mystery" behind the curse, and didn't care to figure it out once the monsters were dead and the treasures looted.
Bad layout. Pretty standard with Paizo stuff, honestly, but this mod is particularly egregious. There's an encounter with a ghostly dwarf monk that includes a two-page stat block (seriously?), but the stats for Manticores are just given as a page number. Boo.
Overall? I recommend it. Just be prepared to do some real work and make it fit your group.