First off, you need to calclight it again, then save. I entered the map with the pixel-effect (if that makes sense, where you edit after calclighting and it makes some parts lighted, others fullbright).
Small details:
-the part where (I assume) you made elevators and put a texture up to look like buttons.. put noclip on the buttons that stick out because if you're walking near the wall you get stuck on them.
-you can delete the bottom of the map (instead of having the building continue down into infinity and put death down half-way). That's not a huge thing, but deleting space not actually being used.
-the buildings aren't "anchored". They're just floating, which ruins the logic in the map.
-I got lost.. many times looking around. All the rooms look similar, and many are identical. there are no outstanding characteristics in any rooms to tell the player where they are. this is useful while playing so you can quickly get to where your opponent is and shoot them in the back, among other things.
-not alot of detail anywhere. textures are basic, etc.
-the staircase is a little thin so you actually have to slow down and position properly to get up them. I'm not saying make them wide enough for two people to run around on, but comfortable enough so they can be used for a getaway.
Good effort, and it's good to see that you don't expect releases from your stuff yet. If you get your hopes too high, any disappointment will make you pissed off and quit for a while, but this way you can learn rather quickly.
Keep working.
