Oh boy. I can rip Abomination Vaults apart. I'll direct you to this thread to start (since the hour is late and the bourbon has been imbibed):
Pathfinder 2E - PF2: Second Attempt Post Mortem.
Synopsis of my opinion: Abomination Vaults is a poorly constructed dungeon crawl with no relevant background, character motivation, or urgency. It features inconsequential encounters, tiny rooms that don't allow good tactical movement, illogical design and layout that was trashed in the editorial stages, and absent of any sort of clues of what is inside.
It is little more than a collection of rooms with no purpose to tie them together, no motivation to go on the quest, no urgency for the plot. It's an assembly of meaningless encounters, forced into a Gamemastery flip-mat design ill-suited for a megadungeon.