Signs; Currently all the signs are floating off from the wall, either give that brush sides, or use a shader so it can display on the wall surface without Z-Flickering. The textures are too low res and are looking bad ingame.
Block lights; Personally I don't like them (I prefer they be embeded or have some sort of frame/trim/edge). If your trying to keep brush count down then I'd suggest you make those lights nonsolid or add some angled clipping around them.
Fans; Their design doesn't fit the environment. They also need clipping (I know you seem to want them to be an environment hazard but).
Level of Detail; Varies a bit, there are some areas that just feel unfinished.
Textures; Alignment issues here and there. Also pipes texture on wall ('e6cyb0rpipes'), Why would you do that? Just looks horrible and amateurish at the moment.
Lighting; Vent lighting is a bit too bright (Even at default gamma). The shadows under the trees near human base are too strong.
Skybox; Light coming from it seems to be wrong colour. Also I'm personally not really a fan of this spacescape.
Hanging Vines; Don't really make sense hanging from ceiling, also feel somewhat out a place.
Benches; There are some misaligned brushes (Where arm rest connects to leg, and the seconds from the bottom back support bar)
Soundscape; May want to consider doing some work on this. Furnace room could be noisy, as could places with numerous pipes/vents.
Waterfall; Could use a shader like the water splash one (The rings of "ripples" when a player walks through water) to better blend where the water contacts the pool below.
Can't comment on gameplay as I haven't played Trem for a while, nor had the opertunity to playtest your map.
Obviously some of this is just my opinion so feel free to ignore it.
I'm sure there's things I've missed but hope this helps. (May edit this post later)
Oops nearly forgot, Nice map Supertanker.
