I actually haven't tried Dead Space. Gameloft games are generally considered the gold standard for shooter controls on iOS and I've found them to be good/acceptable always with the caveat "for a touchscreen device". Do you know if Dead Space controls are better or as good just different?
Better.
Gameloft uses "virtual" joysticks. And I'm really not happy with the inherent weaknesses of that compared with physical joysticks, particularly for a genre of games that plays better with mouselook in the first place!
Dead Space does use a left side virtual d-pad that allows you freedom of finger placement. Since it isn't detecting more than 90 degree direction and distance from where you put your finger down in the up direction (to allow running), there isn't much that can go wrong. It's very basic, and thus works. WASD, essentially, plus running forward. Less ambitious than NOVAs virtual joystick, but also without its frustrations.
What really makes it shine is the right side mouselook, using your finger. On the iPhone, the small screen would make control a bit inaccurate, and the fact that you cover part of your screen with your finger can be annoying on a smaller screen. On the iPad2 however, it works beautifully. Sensitivity and accuracy is mouse-like, the frame rate, even with the improved graphics, is high enough that even an old competitive Quake player is happy - it is a very direct feeling, and good control is achieved with only your thumb down in the corner. You fire by tapping the screen where your finger happens to be. Now, NOVA has mouselook as well, but there you fire your weapon by tapping on a specific fire-button, which not only takes space, but requires you to stop using your finger to move, moving it to the fire button, fire, and then moving it back to an area outside the fire button to rotate your view/aim. It is as if to shoot on a PC game, you had to release the mouse, tap the return button to fire, and then move your hand to the mouse again to aim at a moving target. NOVAs scheme makes it impossible to aim and shoot at the same time. Dead Space still doesn't allow you move your aim and fire at the same time, (theoretically possible with multitouch), but the interruption of your aim is shorter, and thus more tolerable as well as not stealing screen real estate, restricting where you can use your finger to aim or requiring you to hit a particular physical spot to fire.
There are other aspects of the game interface that doesn't work very well unfortunately, but basic movement is the best I've seen so far outside WASD+mouse. Pity about the firing messing up the aim.
