do you mean his visuals generaly or is there anything spcial you wonder ab out. i dont know much about the limitations of the source engine, besides from the texture shader and the static lightning.
anyway it looks nice (the pictures in your post doesnt show up. duno).
but i finaly found sth that could be better:
as you can see there are in almoast every building some parts that are darker, whereas in yours thay have mainly all the same color, maybe that could bring some more contrast.