I have to partially agree with Yathzee.
I never considered the series as horror, it was always more of an action-thriller for me with a few horror-elements sprinkled on top. I mean, jump scares are not horror. It doesn't make you afraid or horrified, it just startles the shit out of you for a small adrenaline-burst! REAL horror is something like the Amnesia or the early Silent Hill games, when it is all about the atmosphere and suspense. The most the Dead Space series had in this regard was only a very few moments in the game when you wandered through the devastated civilian areas in the game, and even then it wasn't oppressive because you were afraid a scary monster would jump at you, but because you looked around in the blood-stained bedrooms and cradles and stopped for a moment to imagine what has happened there. Actually, I would say the game only had any horror to it when you stopped playing and instead just let the atmosphere soak in. Otherwise it was just a shooter with scary monsters and jump-scares.
That said, Dead Space 3 is not exactly a good game even of you look at it as an action game. It is just too damn long, the weapon customization is fun but mostly unnecessary (about 80% of all weapons are either very situational or completely useless), the story is just dumb, like the ridiculously contrived love-triangle "subplot" which got resolved in the dumbest way possible and, well, if I would have to point at the biggest problem in the game, it would be Danik.
That guy is supposed to be our main antagonist for practically the entirety of the game, and yet he is the most unintentionally incompetent bad guy I have ever seen. He has Isaac and co. at gunpoint no less than THREE times, yet every single time he just monologues instead of doing anything more logical, like shooting, and so Isaac gets away in the last second. He is also supposed to be the leader of the Unitologists, yet he is not only in the middle of the damn battlefield, but he doesn't even wear any armor, and he is played up as this really menacing opponent, but in reality the only reason he ever poses a challenge is because in the cut-scenes Isaac is weaker than a little girl and gets beaten up by everyone even though he wrestles with huge-ass necromorphs on a daily basis. Not to mention, Danik suffers from the same ridiculous under-characterization as the rest of the cast, which made some scenes kind of hilarious, when the scene played things up like a character dying was a huge tragedy, but all I could think of was "Who the hell was this guy again? Why is this important? Whatever, let's move on."
Finally, the sound design of the game is also horrible. I actually had to turn the volume on my machine down quite a bit because the constant scare-chords and growling got old really fast.
On the other hand, I liked the first third of the game, navigating in space was surprisingly fun, gathering the history of the ships and the base on the planet from audio- and text-logs was engaging and there were a lot of elements that broke up the monotonicity of the sooting. In the end I would say it is not a bad game, but it it just too damn long and too damn dumb to be really great.