Dead Space 2 is more than just an action game and it's more than a survival horror game -- it's a game that tells a really personal story about a guy who has been seriously scarred by the events around him. That premise alone makes it interesting, but Visceral Games melds it with rewarding combat, shocking enemies, and huge set pieces before tossing it into a world that's truly creepy and scary. I didn't find multiplayer that interesting and would've liked to have seen Isaac stop being an errand boy, but none of that spoils what you're getting here. The shocking moments, the gruesome deaths, and the fun of playing through this experience again and again are what I took away from this one.
Dead Space 2 is an excellent game, and it's well worth your time and money.