Well...there's a little difference between Dead Space and Doom 3 though. Doom 3 shocks the crap out of you, but isn't really scary. Dead Space however, while also using a lot of shock moments, is also scary; you don't just rush through the whole space ship killing necromorphs left and right of you, but you actually start moving tactically and carefully, always ready to shoot the enemy wherever he might appear.
That being said...I liked Dead Space, it's one of the best horror/sci-fi games I've played so far. Sure, it has a couple of flaws (like every game has), for instance, I would have liked more parts in which you interacted with friendly NPCs, but that's just my opinion, and whatever may be, it's a great game;).
Edit: But yeah, Bioshock is still the king of all horror games;).