I haven't played Doom before, but if I had after playing DF, I would've just gone back to DF. Wasn't DF the first game where you could actually look up and down to some degree at least? In Doom the enemy placement wasn't 3D, it was from the front or back or the sides. The most revolutionary gaming moment I remember from playing DF was the first level (Secbase) when I got shot by a stormie from the room above me. I can't wait for the DF JA mod to come out. 3 level demo in 3 weeks *prays* to bring DF into the world with better graphics!
"Size matters not."-Yoda
"There is no emotion; there is peace. There is no ignorance; there is knowledge. There is no passion; there is serenity. There is no death; there is the Force"-the Jedi Code