As others have said, the graphic design, especially the cover, is amazing. 5/5, no question.
I would format the room description slightly differently than the detailed break-outs from it. Maybe italicize the initial room description and leave the detail paragraphs without italics.
It's hard to get more Appendix N than flesh tanks and snake men! And I love the idea of flying away at the end on space pterosaurs. Amazing visuals.
A week-long bonus to carousing is pretty good, if you've got players with both coin and math skills. Still less good than having a bard in the party, though, so it's not out of line.
I think this is the first time I've seen mechanics for betting one's soul, which feels long overdue.
I like the idea of the Duskblade, but I would probably expand its description to also work at dawn and dusk, rather than simply being dependent on the torch timer.
I agree that this is a highly dangerous adventure for Shadowdark, but it'd make an epic one-shot with immaculate Appendix N vibes.