(http://i136.photobucket.com/albums/q175/DJRocketDX/Screenshot_Doom_20101026_111247-1.png)
This is the single most greatest use of software's freelook I've ever seen.
Use more textures. Make it bright and colourful. Don't stick to like 5 textures and have it as your "theme". Try to "Mix & Match".
Oh and make the brightness 255 for everything if you want it to look like a legit MM8BDM map.
I think I see that you're using a sky texture for the walls. Don't do this, ever. It's bad. Just use the Line_Horizon special instead.