Tbh, I kind of expected quite a mess after you mentioned your avantgarde
approach to brushwork and all the error reports, but if one doesn't look too closely, the map is good. Standard bunch of obvious issues like improperly aligned textures (on transitions mainly), empty spaces, portal errors, z-fighting, clipping. But it's a unique theme and well pulled off despite everything, which is nice.
Gameplay seemed okay, except would've been more fun and varied with more weapons (yeah, I know: first map of an episode). The sentinel bit annoyed me a little, though it was no problem on the second try. Overall enough supplies; a bit pressed for ammo at times on skill 2. I think I even found all five secrets (except didn't get the item from the first one).
I'm not much of a fan of the Quoth flashlight, but the darkness section here worked out well. A nice gimmick with good timing.
Hope you're going to touch up on the most blatant issues for the episode release.