We played this as a one-shot around Halloween, and it went great! They didn't visit the gallery, but a player tried to convince Helel that God isn't so bad and everything went to hell just as they found Lum. It was just the right amount of chaos and disturbing imagery.
I played it again more recently with other players, and this time they helped Helel. For their wish, they asked for the Sky Marble. Of course this precipitated the Nightmare Phase, and they had to rush to escape. They barely escaped by removing the door from its hinges (one is a blacksmith, which helped). It was super funny, and they loved outsmarting the scenario!
Also, I first read the module right after the Gamer Blast episode where you ranted for five good minutes about needing a weird little Gollum guy in every dungeon, so seeing the weird Dark Souls-type old man made me laugh out loud, much to the dismay of my sleeping girlfriend.
Thanks for such an awesome time all around :)