What should I expect?

Dead Space 1: Great jump scares. Amazing fucking sense of being utterly alone vibe. Creepy ass music. Sense of no way out. Difficulty on Normal and above. Perfect show of survival horror.

Dead Space 2: More action horroresque. Good jumps here and there. Atmosphere is still decent. Feels a lot like RE5. Still difficult enough to make you want to rage quit.

Dead Space 3: RE6 meets Mass Effect, with jolly cooperation!

Mutated babies. A creature that violates dead bodies till they become mutated monsters. A weird spore spreading person that sits there and makes weird wheezing noises till you murder it.