The fiendish concrete city has the same uncanny feeling of the default g-mod map, where it has the vague shape of a real place, but is unendingly flat and lifeless. You're greeted on entering the map by two lone fiends, slowly making their way towards you across the quake equivalent of rolling hills.
Maybe the defining feature of the map is just how much space there is, and how little the map cares that you see it. Its a very open map in every sense of the word, consisting mostly of a train station and a small cluster of buildings connected to it over a concrete bridge. There is, in theory, a progression to the map, train station to small city, then silver key to gold key to map exit. In practice, this is more of a guideline than a set of rules. The silver key can be skipped entirely in 3 different ways I'm aware of, one possibly intentional, the other unclear. The way weapons are placed around the map too, with several having duplicates, suggests the expectation that there isn't particularly a correct way around the map. Likewise the music, full of softly twanging guitars, gives no sense of urgency or pace to the whole affair.
What's left then is the physical structures of the map, there for you to wander in and admire the little details (a little quake pool table!)
Final rating: Too many spawns/10