Pathfinder Adventure Path: Abomination Vaults

To the Point: Abomination Vaults is a game with Very Specific Tastes.
It's a 9/10 if you absolutely love combat in Pathfinder Second edition, and dislike everything else.
It's an 8/10 if combat is your #1 favorite aspect of role playing games, with everything else a distant second place.
It's a 7/10 if you think combat is amazing and you want more of it than any other aspect in your ttrpg.
It's a 6/10 if you find constant combat to be fun, and don't mind not having anything else to do.
It's a 5/10 if you like combat a whole lot, but maybe want some role playing in your role playing game.
It's a 4/10 if maybe combat is your favorite thing, but not by much.
It's a 3/10 if you think that hey, maybe there's a plot to be discovered here.
It's a 2/10 if you were expecting a character arc.
It's a 1/10 if you wanted something other than to make hp go down on enemy tokens.

To play Abomination Vaults is to embrace with both arms and a loving heart a single aspect of Pathfinder Second Edition.
To run Abomination Vaults is to look at your players and say - with complete seriousness - that while other game masters studied storytelling, you studied the blade.
To truly enjoy your time in the Abomination Vaults, you must be able to maintain a laser focus on the marathon sprint that is eternal combat.

What plot exists is paper thin. The trappings of the city of Otari, the locals, the names, it's all two dimensional cardboard.
You delve into the vaults because you can. You stay because you want to. Your character motivation comes from sitting at the table and holding your character sheet. The game requires a level of buy-in from both players and GM that every other game I've played does not require. You play and fight and run the adventure path because that is the agreement you made by making a character.

And that can be glorious. It can be freeing. To sit down with your friends and say, friends, we are a dungeon delving swat team and by all the gods we are going to delve some dungeons. We are here to murder/delve our way straight to the core of this place and anything that gets in our way is getting pasted to the walls.

If you are a GM and want a story, steer clear. But if you have a pack of barely constrained murderous players who crave blood?
Good hunting, my friend.

I'll be honest, I didn't understand why everyone was raving about this adventure until I read it. The concept and story are nothing new, but the execution is superb. The villains are foreshadowed well, the dungeon levels have distinct themes, all the monsters are there for a reason and make both narrative and thematic sense.

The fights are well balanced. They are difficult without feeling unfair or insurmountable. And there's still roleplaying opportunity even with many of the dungeon denizens!

I'm having a blast running this adventure and it's one of the best Paizo has ever made. I'd put it with the likes of Curse of the Crimson Throne, easily.

Pros: Interesting story and new monsters.
Cons: Insanely difficult and unforgiving combat encounters which required highly optimized party.

This is, top to bottom, one of the best APs Paizo has put out. The only other megadungeon I've ever felt positively about is 13th Age's "Eyes of the Stone Thief", and this tickles me in all the same ways. The adventure is great, and the Foundry module support is absolutely stunning. Well worth the money, even regardless of me not getting discounted for having the original 3 in PDF (which, whatever, sucks but hey).

The changes made in the compilation themselves are great too - adjustments to a couple encounters, improvements in connectivity and layout... It's just all around a stellar package.

Dungeon-crawls aren’t really my thing. But this is the best dungeon-crawl style adventure I’ve seen.

It has an overarching plot driving the exploration, giving the adventurers a sense of purpose and urgency. It’s filled with sub-quests tied to the different factions in dungeon and to the people in the nearby town. It presents a number of entertaining NPCs and role-playing possibilities for the players to take advantage of. (Make sure the party has someone who can speak Undercommon and Aklo!) And it weaves in some mystery-solving, with a scattering of clues about the dungeon’s history (and about the main plot) well-distributed throughout.

It does a nice job of explicitly presenting the dungeon in a dynamic way, describing some of the likely movements of various occupants of the dungeon over time. It introduces “Environmental Cues” to the sidebar descriptions of each level, providing some nice aesthetic guidance for the GM to elaborate on. And unlike the early PF2 APs, it’s pitched at a more reasonable difficulty level.

But the most impressive feature of this dungeon is how organic and well put-together it is. Each room has a history, a reason for why it’s there. The occupants of each room make sense, and tie into the history, and the other occupants of the dungeon, in natural and organic ways. The levels are nicely integrated with each other. It all just makes sense.

I tend to dislike dungeon-crawl-style adventures because they often seem to consist of a bunch of random rooms, filled with random monsters; and if you’re lucky, the monsters on a level might be thematically related to each other, although the levels themselves rarely are. This adventure is the exact opposite of that. And even though dungeon-crawls aren’t my thing, it’s hard to deny that this one is a masterpiece.