I've had several pointing devices, including standard mouse, track ball, and pad.  None comes anywhere close to being as natural and useful a performer as this one.  Its simplicity of design hooks one almost  immediately, and within a few minutes of use, one doesn't want to go back  to the  mundanity of ordinary mice.  Unlike trackballs and most low-end  touch pads, it's very sensitive, and so makes a servicable stepping stone  for grahpic artists on the way to purchasing a more serious graphics  tablet.