Not bad for your first attempt but Dr glass has a point plus I see that 70% of the map is models!

Try making some architecture using brush based work and it will suffice!

for what it is, its dosn't look too bad. The problem is that it
is just a box with some walls and models tossed in. When
you make a map like this you have to try and draw the player into the
situation. Take the new de_train, there are so many things that
make me feel like I am in a real place that is only a smal part of a
huge enviroment.

The best way to do this is with a sky box.
here
is a tutorial

Also, use google serch and try to find some pictures of a simular
place. Add details and dont rely only on props to make your map
look good.