Hi nolcoz! Great job on completing your first map. I've recorded a demo of my blind run on normal mode (using Quakespasm).
In general, I found there was probably too much ammo relative to the number of monsters you have in the map. I was nearly always full on shells and spikes. I ran out of spikes once, but there were rooms nearby with tons of ammo.
For the encounter design, it looks that in general I'm only fighting one type of enemy at a time, and that they come in waves. This made most of the map quite easy to overcome, as there was also generally a lot of room to run backward or strafe around a room to stay out of the way of both projectiles and melee.
To break that up a bit, consider mixing encounters with various enemies. On normal mode, it's nice to feel like we're not running out of ammo, but there's no tension if player has plenty of room to move and are always fully stocked.
Conversely, the first encounter in a small, dark room with two Vores in it takes the difficulty way up. I would suggest: turning the lights up a bit in there, and only have one Vore on normal mode. Opinions may differ on that, but I if you want to keep the difficulty up, consider a Vore and some other monster to go along with it. Whenever a Vore launches a Vore-ball, that's basically another enemy in the room. Given how small the room is, I'm not sure that's appropriate for Normal mode.
As for archicture: love the progression. The rooms are simple, but you're using a lot of interactive elements and surprises. I liked running around in it.
There's one area (upstairs near the Shambler fight) where are a bunch of electrical devices. I'd love to see a little glow around those electronics that shed a tiny bit of light on the geometry around them. And it seems a missed opportunity not to put a little damage trigger on those, so that running around to avoid enemies isn't completely free. That could spice it up a little.
Once again, great job! Looking forward to the release :)
Demo link: http://rhoq.ddns.net/archive/demo/tsotm_rhoq.dem