AS-TheFactory
In General
-TONS more eyecandy
-add things to the level that create depth to the "plot"
-downsize maybe a teensy-weensy bit, b/c right now it seems kinda like toys invading a toy factory; eye candy may fix this problem however
-in general, use lighting and textures that make the factory futuristic, not modern, ala ColdSteel2
-put in moving parts and conveyer belts to look the it's an acutal factory that's actually working, (look in DM-Conveyer for what I mean)
Specifics
-I dunno, but I'd rename it AS-Factory myself, unless that's taken
-change attackers weaponry to Pulse Gun, Rocket Launcher, and Sniper Rifle with 2 ammo packs each
-give the attackers flashlights or searchlights; if they were in a closed cave they wouldn't light a fire because of the smoke
-make the outside more of a battlefield
-the big hole I'd make a tunnel crossing to the other side, to give the impression trucks deliver items to and from the factory; too many facility-type levels have the front of the fortress facing basically a brick wall (AS-Mazon is a prime example)
-make a sniper tower located above the entrance to the factory
-give the Minigun foxholes a button to their left or right to which they can dodge and press and immediately a thick sheet of metal will cover the turret's eye hole, so they can block rockets, etc.
-don't make the hole through which launched attackers can fall so gapingly big; make it a ventilation shaft sorta thing
-collision radius of the red button is WAY too big
-do you really want those double doors' texture to be a box? :S
-make the end objective to destory the main generator and the back-up generator; most factories wouldn't have a "Push this button to deactivate the factory" thing; generators should be able to be destroyed in any order
After all that, the good points
-big = NO spam (most significant plus)
-Minigun turrets; used well they can be very effective
-tons of secret passages; at least I assume all the ventilation shafts are secret tunnels that can be used :S; if not, make it so! (to a certain extent at least)
All in all, one of the better beta maps I've seen.