Familiarity has powerful effects on the ease of using a product. For example, consider a pointing device for a computer, whether it be a mouse, a touch pad, or a trackball. Someone who has exclusively used a mouse and never used a touch pad will almost certainly encounter difficulty and frustration when they try to use a touch pad. But after a sufficient time using the touch pad, she may actually grow to prefer it to a mouse. This concept applies to just about any product, including computer operating systems, e-mail software, toothbrushes, and even food.
Ease of use, therefore, depends not just on the person but on how familiar they have grown with the product. A product may intrinsically be easier to use than a competing product, but temporarily be more difficult for some users. As a consumer, whenever I have encountered this situation, I have generally felt a strong inclination to learn the unfamiliar product. I face short-term frustration, but the long-term benefits often are well worth the effort. But other people are much more reluctant to invest the time and effort to realize the long-term benefits. In fact, some people don't even seem to understand the distinction between intrinsic and temporary ease of use.
A product manager faces some interesting questions with such products. To what extent should the product features enhance intrinsic ease of use versus catering to those in the market who want a familiar user interface? Perhaps the product manager should segment the market as follows:
"Adventurous Learner" - excited to learn a new user interface for its own sake
"Pragmatic Learner" - willing to learn a new user interface for long-term benefit
"Reluctant Learner" - requires prodding to learn new user interface
"Resistant Learner" - will actively resist learning new user interface
This market segmentation helps the product manager to formulate ease of use requirements that ensure the product's user interface will appeal to a sufficiently large market. The company can bring in product testers that represent each of the target segments.
I realize that these observations resemble those in Geoffrey Moore's Crossing the Chasm. A difference is the emphasis on user interface rather than on disruptive technology.