[SP] The Chamber of Silence
This map could have worked with just a bsp alone
As for the map itself
first, it was too dark...I can't be the only one who is bothered by all this black and then only a few small lights
the blue gel was a nice idea, but you should have somehow notice us in the map that the blue gel doesn't stick to the black walls, i thought it was a bug at first
the rest was okay i guess
lastly, this could have fit into a smaller map, something so big is just confusing
I may have simply done it wrong, but...
If that's the intended way to do it, you might want to rethink it a bit.
Interesting map though, I liked the bit with the gel.
Butterfingers - http://forums.thinking.withportals.com/post86935.html#p86935
And seriously consider watching:
Let's Break This Map - http://www.youtube.com/playlist?list=PLF25FB7F63D2CBFDF
Too elementar and darkish, but there's a puzzle in there... you might want to try reducing the room size, and doublecheck those textures, because in a less boxy enviroment that puzzle be even better.
And if you are supposed to
Thanks for all the comments guys! 
@Forehad58: I have never even heard of the hovering redirection cube bug, so yes, it can be completed without that. 
@Kibate and xdiesp: Thanks for the feedback, I'll take it all on board and will make those alterations in the next version of the map. The reason it's so dark is because I couldn't figure out how to create a single lighting entity that covers the entire room with settings that match the default brightness level/setting after adding in the entry and exit lifts, which is what I wanted, but I'll try and figure it out when I next edit the map.
Once again, thanks for the comments! 