Ok, I'm gonna preface by saying this map is actually pretty good layout and even visual wise. It still has some consistant problems, but I'll just go over em ;P
So, this map is definitely over scaled in a few indoor place, but that's ok for now. I must warn against just using models to build cover, I made the same mistake for a while. its not a good mistake.
Here's an example of an indoor place that could use something in it to make it more exciting. like stairs or some sort of height variation:
And in this cave, you could put some kinda natural or geometrical thing to give the offense cover and really spice up the area:
Another issue in those two screenshots is the lighting. remember to turn off the shadow for all the light props, to give it a better transition, and the cave tunnel system is just wayyy too bright. look at dust bowl, its kinda dark and murky in there. you don't necessarily have to make it that dark, but maybe not have so many light there.
This is kinda my personal opinion, but this is an example of a prop that probably would be better done with brush work. It just doesn't ft with it's weird angles.
Hope this helps! ;P