I've played it, and it's really quite boring! The outdoor area does look good and gives a great impression of being hot and barren. However the interiors really let it down- the windows are really too small to be useful, the rooms inside are usually just boxes with a few props and badly placed VIS-blocking wall, and the tall building with the ladder just doesn't work! (talking of which, most of your ladders don't work very well at all, especially the one leading to the RPG, which has quite fiddly little platforms to get to). Also, I didn't quite understand who'd put those huge concrete tubes on the roof, and what you can do with them?!
All in all, this could be quite fun if the buildings were redesigned- the exteriors look fine, but the interiors are just crap :wink:
The skybox buildings also seem to be larger than they should be, though they do look good otherwise. Also scale down the sand texture outside the level.