Brilliant stuff from usability expert John Rhodes:
OLD Ease of Learning: How fast can a user who has never seen the user interface before learn it sufficiently well to accomplish basic tasks?
NEW Ease of Doing: How fast can a user accomplish the desired task? How much time? How much energy applied per unit of measured time?
Why better? Takes into consideration users doing something versus knowing how to get it done; practical and concrete measures; accounts for situations where learning is not needed nor desired. Deliberately factors out the need for learning, education, or necessary assistance.
Read the full post: Usability Redefined