I saw a presentation recently on the controls for
Warhammer 40,000: Carnage, and downloaded the game to try it out. I'm not sure the game is my thing, but it's a mobile platformer with on-screen controls that is really, surprisingly responsive.
The thing is, you don't technically have to press the buttons to perform an action. Each button is just the visual representation at the center of a slice of screen-space, and pressing anywhere in that sector will perform the action (or sliding your thumb from one to another).
And according to the presentation, the button locations were chosen specifically so your thumb would be in a very different position for each one (extended upward, extended horizontally, or tucked into a corner). That was supposedly an effort to get muscle memory to make up for the touch screen's lack of tactile feedback.
Personally, I was pretty surprised by how well the controls worked. And it's an interesting alternative to the "standard" onscreen control scheme, which puts everything in one horizontal line (and tends, for me, to lead to input mistakes).
That being said, I do also love
Kero Blaster's control scheme, and the way it looks and acts like physical switches.