[vacri]

My first impression on viewing the controller is that reporting the 'location' of the thumb is going to be hard. Unlike a joystick or mouse that has a well-defined point, the thumb touches over a large area. You can find the centroid of this area - and the area will change size and shape as the thumb is rolled around. Different people will roll their thumbs differently, and there may be a mismatch between intent and physical interaction.

It'll be interesting to see how well they manage to deal with this.

[PhasmaFelis]

I suspect that will be a feature, not a bug. I already use finger-rolling on my laptop trackpad when I need pixel-level precision. For noobs, the difference probably won't be noticeable; for experts, I expect they'll be using that technique on purpose.