I think everything that needs to be said about it has been said already. It's atmospheric, polished, fun, and you should check it out if you haven't already. You may notice that "scary" was missing from that list, so you could think I'm damning it with fine praise, but Dead Space shoots more for tension than scariness. I think that might be part of its widespread appeal; even people who don't typically like horror games can enjoy it after getting in the groove.