I believe Fitzgerald to be the finest female popular singer of the recording era, and in the top two or three overall (up there with Sinatra and Crosby). Her voice was smooth and pure and boasted an incredible range. She could also sing with passion without shouting or without performing what I call "vocal gymnastics" ("love" is a one syllable word, people!). I have noticed how many guest coaches on American Idol this year have suggested that the contestants "just sing the melody." This is a lesson one could learn from listening to Ella Fitzgerald.
Fitzgerald herself did not like to be described as a "jazz vocalist." She considered herself to be a pop singer first and foremost. Indeed, her finest recordings, in my opinion, are the "American Songbook" series from Verve Records, where Fitzgerald sings the popular songs of Gershwin, Porter, Rogers and Hart, Harold Arlen, and various other great songwriters. While oftentimes singing more "jazzy" in live performances (see the "How High the Moon" recording at Powerline), her studio recordings are more conventional and, in my opinion, more satisfying.
You'll note that the postage stamp is part of a series promoting "Black Heritage." I don't know of the overall merits of this series, but I am sorry to see Ella Fitzgerald be part of it. Ella Fitzgerald was too good, and too important to the history of popular music, to be relegated to "Black Heritage." Ella Fitzgerald is not part of simply Black heritage. She is part of American heritage. If she is important enough to be celebrated in a U.S. postage stamp, and I believe she is, she is important enough to be celebrated for her contributions as an American to America, not just a black American to black America.