a few other things I'd like to see adjusted:
1) too often high health fiends(pitdrones) come to attack. I think if you were to double the number of fiends and half their health, it would feel a bit better. Put in some surprises for introducing these fiends, like bookcases that slide open with the enemies hidden inside.
2) the slipgates sometimes warp you directly in a pathway, perhaps you should have the destinations be a little in the air out of the path so there are no accidental telefragging.
3) the jumppads are kind of weak, its obvious they are air tunnels with lesser power. The jumppad should only give a strong boost at the very bottom. I am unsure if the upward force applies while standing on the ground, but if it doesn't, then stepping on a jumppad should trigger an invisible platform that rises a unit or two, then immediately drops, so the player is set in air.
4) the body of water below the 2 buttons aren't entirely obvious they'll kill you, a bed of spikes or some indication you shouldn't jump down there would help.
5) turn the brightness down obviously, but place a minor red flicker effect light so the flames actually feel like they're effecting the world.
Overall the map is very nice, it seems short but that may be just an indication of wanting more. I would love to see a sequel with a bit higher r_speeds. The map feels like Quake, but while I don't get the feeling of claustrophobia in Quake, I do get a feeling of it in this map.