iamloner, I love that you're learning to map, but while you're still in the learning phase of mapping, can you perhaps post all your test maps and incomplete maps in one thread? The people here are willing to help you learn, but they don't like it when the threads they create with large, finished maps, and other threads where large, quality maps are in progression are pushed down by newcomers making a new thread each time they have a new small map to show off. I'm not having a go at you; other people have done this recently as well, which makes it all the more important to nip it at the bud. You're ok for now, but please dont' make a new thread for your 4th map, at least not until it's finished
Having said that, I looked at the map, it was a bit uneasy when the map was only 4kb (by comparison, the vast majority of maps these days are over 500kb and most are closer to 1000kb). So looking at the map in mapster, it only has one small room, and a lot of empty space. It's very hard for us to criticize what you've done, when you haven't done anything for us to criticize!
Nevertheless, I did criticize that one room you did, which can be seen in the image below:
Other comments:
The scaling is good, in fact, those cubicles are the tiniest bit too small, but don't worry about that. Shading is going to be your weak point based on what I've seen so far from your work. Don't underestimate shading; it can make the dullest, emptiest maps look full, exciting and dynamic. Another thing I'd recommend to you is to have height variation. Rooms need to be different sizes rather than everything having the same floor and same ceiling. Make some stairs, some lifts or something which take the player to rooms which are higher than other rooms, and make it so that the player can see the rooms below from the rooms above with some windows to him a sense of location and progression. In fact, put in lots of windows even if you can't actually look out them (fake windows) which would help fill up empty wall space, and don't forget to put in lots of lights on the ceiling (the light textures are near the top).
But try doing a decent amount of work before asking people for criticism. The more you do, the more people will be able to help.
Edit:
AndI just realized something, you're not planning to make the map only as big as the empty space you've put in there have you? 
That's tiny!!! Your map needs to be like 10 times bigger than that. Otherwise there is no point in releasing it, because no one's going to play it. Even the pro mappers can hardly get away with making something so small.