When I got "Dead Space" I gave the game a score of 10.0
Since I have beaten the game, I would give it a 9.0
A few things knock the score down a bit...

(SPOILERS)

1. The Asteroid Shooting
2. The Outside of ship Boss

... nearly killed the game for me -- I am hoping Dead Space 2 will not add things like that. But "Dead Space" is still a rockin' game :)