Doom 3 at it's own was a bit "meh". As far as scarefactor attempts, System Shock series does it way better.
However, I remember playing Doom 3 on a LAN with a downloaded co-op mod. 4 players, maxed out difficulty and the game became utterly wonderful :D
I really recommend people trying it out if they ever go to a LAN.

While I think that's an absolutely fair critique (and the AI was admittedly, absolutely atrocious and the pop scares did get old), I think that's part of the reason I liked the game. It was in many ways a throwback game, just a different kind of throwback than say Serious Sam 2 (which had more of a Doom 2 feel, whereas this reminded me more of Quake 2 and System Shock 2 if it was a strict FPS). I used to like FPS's. I generally don't anymore. The modern ones (esp. the squad based ones) are so detail oriented that they annoy me.
Another thing, while I think D3 is great, it's admittedly nothing like D1 and D2. I think Quake 4 (which I also loved) did a better job at continuing its respective franchise.

I had fun with Doom 3 and its expansion episode, but anyone who thinks it's better than Half-life 2 is crazy. Half-life 2 had its flaws and was a little drawn out in some parts, but overall it was way more revolutionary in terms of visuals, presenting believable characters, and telling a coherent story.
I loved reluctantly creeping through the dark not knowing what's hiding in the shadows in the first few levels in Doom 3, but after a while, the game lost focus. Once you built an arsenal and realized the gameplay pattern of how enemies will attack and the frequency of health/armor pickups distribution, Doom 3 just became another run-and-gun shooter. Which would be fine, except that it wasn't really a pick up and play shooter like its predecessors were either. There was a lot more exposition and cutscenes that interrupted the shooting than I liked if I'm going to consider it an oldschool shooter game.
Despite it's shortcomings I played through Doom 3 twice and would probably play it again someday.

As a Doom game? Not a chance in the world.
As a survival horror? Not bad but not good either.
It felt like a tech demo more then an actual game just like Rage probably will.

You're crazy. People just have different opinions when weighing the fun factor. Half-Life 2 just didn't come off as anything other than a generic shooter with great physics and facial animations.

I don't like to overanalyze games. I just know this is one of my favourite shooters. :)

I think Doom3 was okay, if considered a stand-alone game, it just wasn't really for me. I'm not a big fan of the "dark-and-grungy-oh-look- a-hideous-monster-just-jumped-in-your-face-from-out-of-friggin-nowhere-and-by-the-way-you're-out-of-ammo" genre. But some people are, and for them, I'm sure it's a great game.
However, when I bought it, I was expecting a continuation of the Doom series, with similar gameplay to its predecessors. On that level, the game failed miserably, in my opinion. I'm sure it's an okay game, it just isn't a Doom game.

Wasn't bad for me. Just got repetitive like every shooter out there.

It had a some major failings. The weapons needed flash lights of their own. The chaingun should have been able to fire more than 60 rounds at one time. The game should have used the fact that enemies could teleport in to create random spawn points - and thus add in some vital replay potential. There was far too much ammo. The shotgun had all the range of a melee weapon and the limited multiplayer wasn't worth bothering with.
Those aren't the kinds of failings you'd expect from ID. But those points aside it still managed to be a bloody good game.

Doom 3 was fun for awhile, but it started failing to be a good survival horror game at some point, though it's been too long for me to remember which point. The game just got really predictable, and that killed any fun I had before that point.

Was it the part where some zombie/demon jumped out of a closet/appeared out of thin air when you got to a certain point, or the part where a zombie/demon jumped out of a closet/appeared out of thin air when you picked up a weapon/armor/ammo/item, or the part where a zombie/demon jumped out of a closet/appeared out of thin air when you pressed a button on a computer panel?
And lets not forget the rules of enemies appearing:
If a zombie/demon jumps out of a closet, it's either:
1. Behind you.
2. Many closets around you.
3. In a closet ahead of you that opens in front of you.
4. Dark.
5. All of the above, or at least a couple of the above.
If a zombie/demon appears out of thin air, it's either:
1. In a pipe above you, and you can see/hear them.
2. In a room ahead, which means they may be a boss.
3. Behind you.
4. In some other room, and they come to you.
5. Dark.
6. Sometimes, a few combinations of the numbers above, but never all of the above.
There is no other way zombies/demons appear, so please pick what bothered you the most ;)

Mostly just that monsters pop up whenever you do anything important, and the pacing is almost always the same. Godammit, it's much creepier if you press a button to open a door, and *nothing scary happens*, and it's much creepier if you don't know when they're coming out. After a point, you can just point at a particular piece of armor, or a button and say, 'Something's going to get me there.' You can give a whole bunch of examples about different ways they come at you, but you can pretty reliably guess when something will try to get you.

But that's why I said closet. Big scary monsters jump from closets. What, you aren't ID's target audience for Doom 3? (4 year olds)
Only ID's target audience could be scared from Dark 3.

Don't ya'll get it!? The monsters come out of the closet!!! lol, id you stupid asses. =)

You guys have to play Last Man Standing co-op. It's awesome. Get a mic, and start yelling to friends "LOOK OUT CACO BEHIND!"
It's just very very good. There are also some other mods worth looking out for. Commander Doom is a pretty fun singleplayer mod, a bit gimmicky but nevertheless fun. And DungeonDoom is worth buying Doom 3 just to play it, thanks to huge replay value.
Also, if you really want to play Doom 3, but never got around to finishing it, use this mod:
http://doom3.filefront.com/file/Ultimate_Mod;76555
I know the name is cheesy, but trust me, a lot of work went into this mod. It features (are you ready?):
- Intelligent spawning system
- Flamethrower
- Grav gun
- Bullet time
- Night vision
- Forcefield
- Dual pistols
- Railgun
One thing though: I recommend you guys tweak the damage of the flamethrower. As it is, the Flamethrower is insanely overpowered. I mean, REALLY INSANELY overpowered, and it doesn't require ammo.
This mod is sick. I've yet to complete it on Veteran because it is so difficult. Even though you have a lot of new gadgets, the monsters just keep on coming, and at times you'll simply be forced to run, especially early on in the game. If you thought Doom 3 was easy because it gave you too much ammo, this mod will kill you because you will be stuck with practically no ammo for the early parts of the game.
Play this mod. Do yourselves this favor.