Mhhm seems ok.. here is my ideas
1. Non stop tremor textures in this case is a bit annoying, overall Tremor textures aren't bad persay, but the exclusive use of them grates on my eyes a bit.
2. One thing i notice is that almost everything is 90 degree angles (rectangles) to make a more pleasing effect brake up some of those angles or at least add more detail on the walls.
3. I actually don't think it is too dark from what I see of the photos, Tremulous is meant to be a dark game.