doom with a controller is awesome to play, much better and faster than keyboard only
Ive never played doom with keyboard & mouse, only with keyboard
it just doesnt feel right to aim with a mouse in doom (or duke3d) because its not true 3d and you cant look up and down (you can but it looks ugly)
there is thread already asking for classic 3DR games on xbla, but they replied they are too lazy to port a game and they dont like consoles at all if I remember correctly
here is the thread:
http://forums.3drealms.com/vb/showthread.php?t=17097
duke3d on xbla would rock