I guess it depends when you started. I couldn't play Doom when it first came out as my PC wasn't powerful enough.. but i remember trying it on my friend's new £2000 pc and being blown away.
A little later when could upgrade my PC I raced out and bought Doom2. I still don't think ANY game since then has matched the amazement I got from the graphics... it was stunning.
Using something like the doomsday engine doesn't bring back any of that kind of feeling.. but the smoothing makes it look a little less ugly, the mouselook makes it feel more natural now, and i really like having realtime lighting... it almost has a kind of beauty when 50 fireballs are lighting up a dark room.
As for DNF... i'll believe it when i see it ;-)

Man, I got DN3D + Plutonium Pak somewhere on disc....heh.
Dang, makes me feel...old....

Don't feel too old, i use the plutonium pack every time i want to 'splode some alien brain head thingies.

3DR wouldn't pay GOG to host the files. GOG would pay 3DR for the right to host the files and sell copies. 3DR just makes more money hosting it themselves and selling it directly.

is it available for digital download and with no drm, the soundtrack, and etc via 3DRealms? I didn't think so. You still have to pay $$ for the soundtrack separately so I doubt we'll ever see The Duke on GOG.

I'm pretty sure thats not how it works. Like steam I'm sure behind the scenes publishers pay for the right to have their game hosted here.