@ colte: most important thing that I notice is that it's indeed too dark for CS:GO. Possibly not enough cover, but that really depends on what kind of area this is and more importantly how it plays out in gameplay tests. There is the long corridor in Dust 2 that doesn't have a lot of cover either, but it works.
Other than that, looks like a good start! But another piece of advice, don't go too much into detailing if you only have a single area. Try blocking out the layout first, making sure that it plays well. It's a lot easier to make changes to the layout if your level is just made of big blocks.