Ken Burns' panoramic 10-part essay on `America's music.' Jazz, says narrator Keith David, is `creation on the spot.' Not so with this documentary series: It took six years to produce and featured some 500 pieces of music and 75 interviewees. The opinions of the primary one, Wynton Marsalis (billed as `senior creative consultant'), riled a number of critics. But few could dispute the genius of Burns' two key `Jazz' artists, Louis Armstrong and Duke Ellington.