You don't have to add 3d detail to everything guys. Alot of things you can use texture for. Even though the walls on his buildings don't have 3d detail doesn't mean he can't use window textures, door textures, etc. It's better to do that instead of modeling in a windows or door and adding texture to those later. If you are using the halo 2 bitmap source for this map then you will be fine. Just don't use a plain brick texture for those non detailed walls on your buildings.

I like the model though, keep it up!