It looks very blocky so far. The problem with submitting a map in progress, is that we dont know which things are done and which are subject to change. For example, you could use texture lights instead of light entities.
Give the walls in the big rooms some inclination so it looks less blocky. I'd also recommend using different textures for walls and ceiling, but I assume it's your intention to do so later...
There are also some places where you seem to have used the hollow or carve tool with cylinders... it's not a recommended thing to do