Something I've been working on

So I've been getting back in to mapping recently. I started on this here map recently but I've hit a bit of mapper's block. I guess I'm looking for feedback on what I've got now and some ideas of where I should go with it next.

Little heads up, it's still very early in progress. There's no exit, detail is practically nonexistent, and the texture theme is kind of... everywhere as I'm trying different styles and seeing which ones I like best. Should work in Boom compatible source ports and it uses the CC4 texture pack which I've included in the zip folder until I finish the map and start merging textures.

http://speedy.sh/FJM52/earlyWIP.zip