I don't have a Youtube video up yet, for obvious reasons, but I wanted to chime in now and thank Wouter for the screenshots! I got the first 44 secrets unaided (over the course of six and a half hours and only on normal, but I'm still happy with myself), and the next four with some resourceful poking around (restarting the map to check a thing or two, noclipping a few times to rule out dead ends), but the last two eluded me for a long time and I eventually had to admit defeat. Wouter's screenshots helped me find them; it turns out they were in areas I thought I'd already thoroughly searched, and if it weren't for those shots I'd never have thought to go back. I'm grateful for the effort put into the readme, but trying to attach the text descriptions to the secrets I'd already found was too far beyond my mental faculties. I'm dopey, I need pictures. :)
As far as map feedback, I'll have my first-play video up sometime in the coming week (I hope), but basically, a mind-blowing accomplishment! The architecture, the texturing, the sense of "thickness", layer after layer of construction one epoch after another, the sound design (holy shit the sound design), and of course the secrets. Cute shoutouts to community members, tons of fun rhymes, mechanisms left right and center. Goes to show how much map you can pack into an 8k cube. I'm still reeling.
On the critical side: the loop-de-loop roundabout flow, while providing a great "lost in an alien dimension" sensation for just playing start-to-finish (i.e. like a normal person), roughed me up a bit in the hunt for secrets. But I suppose that is my own fault; Sepulcher really drove home how much of my frustration in secret canvassing is my own psychology fighting against me.
I also feel like the end fight might have benefited from a Fire Shambler or Boglord? Something big, in other words. Felt like it could have been more of an event, given the scope of the adventure before it.
Finally, as much as I understand the need for promotion, having followed sock on Twitter for a bit now I did feel like the impact of some of the more striking secret areas was diminished by having seen preview screenshots. Still put a smile on my face to actually get into them, but I think I'd have been positively floored if I didn't immediately recognize the areas.
All in all something to be immensely proud of! Now if you'll excuse me I have almost nine hours of video to edit.