So I played through your map (sort of, I didnt feel like wandering around trying to find stuff so i used level editor to find keys ^^). I am going to give some critique, in hope it is constructive.
First of all, my framerates dropped a little at some points, I checked the map in the editor and noticed you used only 14 point lights in the whole map. Using only light entities to make a room look bright is bound to lag. And without connecting the lamps into point lights, the lighting looks unnatural (if you don't spam 10 lamps in a single room). Even though you explained the reason for the lit lamps there are still so many
Then there was no box light in the map, meaning the dark spots in the rooms look unnatural (it could be fixed with point lights too ofc, but single box light helps a lot).
I didn't feel like going throughout on the letters, but I think I got the most out and its good stuff you have come up with. First I was confused by the amount of names, and i didn't know who I was until that one letter that explained a lot of whats happening.
There was some minor placement problems what Dark Knight found too, some of the lights shined through walls and such. Also try using fixed axis billboards for the windows. Its more work but when done right, it can look awesome.
But man did you do a good job placing entities! I loved the amount of detailed shelves all around the place (I know very well how painful it is to put books into shelves!) and where ever I looked there was something. But even with the sheer amount of stuff you placed it still looked natural.
In the end I think you are off to a good start with this. The story is something little different to the most seen here. Just do some minor tweaking to the lighting and it could become even more atmospheric. Don't give up on this and have fun mapping.