I've installed the game on both my 9800 PRO and my bro's 9500 PRO. The game looks great, and I get a steady 60 FPS @ 1024 x 768 with Medium quality. The GUI is neat and clean, the settings are simplified and everything is just wrapped up really nicely in terms of interface.
My biggest gripe right now is that I cannot do anything about the script. I add in "seta r_displayrefresh "90" " to enable 90 Hz for my refreshrate and after I run the game and exit.. the game removes them from my config file

I guess this is the end of script editing?
As for the game itself, it's great! I like it a lot. The little details like the jolting when you're getting hit is a very nice effect. The scripted "Boo" type scares remind me a lot of RE which are nice.
Well, I'm out for now. But I still haven't played enough to give a fair rating yet.
Addition after a bit more playing:
Does this game bring something new to the table? No. Was I disappointed? No, because I didn't let the hype carry me away. I did not see this FPS as a "Far Cry Killer" or even an equivalent. I've said it before, I was hyped about this game for its engine and as a sign for new games to come.
As for the game itself. It's very atmospheric, and I really felt being immersed into the darkness. As BWX mentioned, this game is well polished. Virtually bugless so far. Not a single issue of clipping or glitching in the game at all. I cannot say the same for Far Cry.
A lot of people mention AI issues, but I'm not seeing a problem yet, but that could be because I haven't gotten very deep into it yet. So far, the zombie civilians act accordingly (mindless and in a "Crush. Kill. Destroy" mode.) The zombie marines are attacking at a more "active" method with ducking and strafing behind walls, but they're not being overly protective of themselves like the enemies in Far Cry, but why would they? They're zombies. The Imps.. Well, in the caste of demons, they're the lowest ranking demon.. the foot soldier and they're not acting to clever, which I expect.
The weapons are well, classic Doom weapons. Fists are uber powerful. I just wish I didn't disintegrate my enemies with my punches.

The pistol would have been nicer as a semi-automatic, the shotgun feels underpowered, the plasma gun's firing rate is slower than I remembered in classic Doom, the rocket launcher is just about right, the chaingun is overpowered.. (It's too good in MP), the P90 like machine gun thing is alright as well. I haven't seen the Chainsaw or BFG yet.
Multiplayer was a waste of time. I tried it with my brother and it just ... blah. Why did ID throw it in? I know they shouldn't have made a great MP which would steal away from Quake 4, but come on.. do something else besides basic DM. I thought they said they wanted to do something unique with a 4 player DM, but...nothing. This game shouldn't be purchased for DM, cuz it's just wrong as is. A co-op would have been much appreciated more, I hope they release one once they get one working with X-Box or somebody makes a mod.
Graphically, I liked it. The level design was good enough to maintain a steady framerate which is very important. I did suffer some "mini pauses", but they eliminated themselves as time progressed. (I have a GB of RAM too) The engine worked well with my bro's 9500 PRO. It looked nice even without bump mapping, medium quality and at 800 x 600.
Sound was great, the voice acting is by far one of the best voice acting I've heard.
I would have liked the enemies to take more damage or act like they did in the Doom 3 alpha... Zombies are unkillable unless you blow off their face, shot to the head, or incapacitated by devastating shots to the body.
After judging this game... I give it an 8/10
"Doom 3 isn't Far Cry 2, and it's not meant to be."