I can't stand tiny buttons whose clickable area is limited to the graphic itself, just virtually unusable. I'm a mobile app programmer (or used to be, anyway) and whenever I got handed a design like this to implement I would always make the tappable area larger than the graphic itself - and then have to deal with angry designers who insisted that was a violation of their design principles. On more than one occasion, I was ordered by managers to undo the already-implemented larger tappable regions, on the hilarious grounds that implementing them would take too long.