I tried running other operating systems on my Apple laptop with the large touch-pad and none of the other laptops I tested were able to reduce the sensitivity or do typing detection properly to prevent random mouse clicks while I type. With the large touch-pad, part of my palm rests on the touch-pad while typing. Without good detection the laptop becomes almost useless.

It's such a minor thing, but it is the major reason I went back to OS X over Linux. It was also the item that really made me appreciate how much detail Apple puts into their interfaces.