It's not constantly spinning, but enough to make me want to quit playing. Playing a stealth shooter without precision and control over your own character really drives me away from this game.
Also this is not a DRM issue, I installed this game fresh from the box and it stutters. Then I went online and saw 'stutter fix' posted by some people, then I reinstalled the game and applied the 'crack fix' but it made no difference. It is definately a loading problem, and 'crazy mouse turning' is the most visible result.