I notice that a lot of the maps are using a dark blue/black/dark gray color for the majority of the settings. NS1 had a lot of maps with a more beiege or tan color (like Veil and Eclipse). I suggest someone make more use of this because there is a lack of that atmosphere.
The new maps with the darker/more blue and black appearance look good though. They really look like the Alien films.
How long does it take to complete a map generally? I have never used a map editor or created a map, but if it is possible to learn then I'd probably try. However, it seems like something that is not easy to pick up.
Also I posted earlier about NS2_rats in the style of cs_rats from Counter-Strike. Still a great idea.