Dead Space is an outstanding, outstanding game. First good product that came out after a rather mediocre summer of video-games. It wasn't long -- about ten hours -- but it didn't try to be longer to squeeze any more out of the game. The plot was good, the voice-acting was awesome, and the gameplay never got old. It was a lot more than the usual space-horror games tried to be, with the inclusion of enemies that don't have measurable or predictable damage standards (which means you'll be blasting corpses long after they're dead, because even the ones you've decapitated have a habit of coming back to eat you), zero-gravity space exploration, and the use of time-stasis and telekinesis.
There's a lot more to this game than the ads and the reviews mention.
I can't wait for the sequel.