can't recall this specific environment from oblivion, probably because I never completed it, what type of light are you using for the scene? point or sky? I'm seeing skylight at low brightness and the problem with skylight without any other point lights in the scene is that the lighting still seems washed out.
Did you build all of this with BSPs? Or static meshes? if meshes the texture is kind of laying weird on the corners where the plane direction changes are. If BSP, well that's just the way it'll usually look.
Good start, cant wait to see it populated.