In fact, at least six factors make the iPod such a hit:
cool-looking hardware; a fun-to-use, variable-speed scroll
wheel; an ultrasimple software menu; effortless song
synchronization with Mac or Windows; seamless, rock-solid
integration with an online music store (iTunes); and a universe
of accessories. Mess up any aspect of the formula, and your
iPod killer is doomed to market-share crumbs.