1. Scare factor - Will this be more than shadows? My top two "scare" games are System Shock and System Shock 2 respectively. It will have to beat those to scare.
I expect Doom3 to make those SS2 monkeys and crawly things look like a group of old women with nitting needles.
2. Gameplay - How creative will/won't the gameplay be? I just finished that %@%#$% Ultimate Doom collection and I have definitely mellowed a bit on the mindless action bit. I am not expecting a Deus Ex here, but I hope it is on par with Half-Life.
Yes, it does indeed look like there will be some interaction with the other non player characters throughout the game to keep the story alive...though the npc's may not make it.
3. The "Far Cry" factor. How big will the levels ultimately be and how creative (open ended) can my approaches be?
This is something that I am worried about myself. id has pushed the limit to make the levels as large as possible. Keep in mind that on ultra quality the graphics card that can run at that level of detail has not been made yet. And, a 64MB card is the minimum just to load up the low res maps. My guess is that there will be lots of detail and levels that are more than just two corridors. I too am hoping that the experience in Quake II is repeated to allow levels to be entered from different directions, and for them to be "open" like in Ground Zero when after lowering a bridge were able to freely move throughout over 1/2 of the levels in the entire game.
Also, I don't care how long the game is cause I'm gonna play it over and over for many years to come. Now that I have a graphics card and computer to handle Quake II on 1600x1200 with full detail I am having a great experience even though I have played the game through so many times before. I'm sure it will be the same with Doom3.