It isn't scary, and the Doom 3 engine is only good for corridors so the level design sucks.
It's not a horrible game, just incredibly generic and boring, it doesn't help that they made the art design more subdued in comparison to its predecessors and redesigned the monsters into their "cool" counterparts where they look just like any other monster in the FPS scene.
It feels very, very generic, on the other hand, the shooting is satisfying and it has a gloomy atmosphere with impressive lighting (for 2004).
Unless you want to play a glorified tech demo, I suggest you pass it over, it's just id Tech 4 with a small layer of gloss in order to justify putting it on store shelves.
EDIT: The graphics don't stand up by today's standards, the textures are relatively low res and the character models are blocky, the only reason it still might look good is because the lighting tends to make it more difficult to see the flaws in he graphical design, in other words, it's too dark to fucking see anything.