I have to Dead Space for PS3 which is still unopened after over a year. I'll get to that sometime later.
I hope you're aware that Dead Space for Android/iOS is completely different than Dead Space for consoles. It's a original game that takes place between Dead Space 1 and 2, with a different progtagonist.
Also Dead Space isn't perfect, but I'd definitely say its worth 50 cents. As far as touchscreen-based shooters go, it's definitely the best I've played so far, and I hope more games adopt its control scheme instead of using onscreen buttons.