David Hajdu in The New Republic:
I’m not blaming Andy Griffith—not the actor, who died this week in his home state of North Carolina at 86, the age he has always seemed to me. It’s not his fault that the theme song to The Andy Griffith Show had the impact that it had on me—and, I presume, on others who found themselves watching the series at some point during in its eight-year network run in the 1960s or in its perpetual cycle of cable reruns. The tune is, without question, one of the catchiest trifles ever composed for commercial consumption. It’s bouncy and swinging, with an angular, syncopated melody. In the canonical rendition for the opening and closing credits of the show, the tune is whistled (probably by Fed Lowery, who whistled professionally for the Hollywood studios, perhaps by the song’s composer Earl Hagen) over accompaniment by a spare little guitar-based rhythm section. There were actually two versions, slightly different—the original had a bit more snap—done for the original black-and-white credits and the later color credits (and it’s possible that Lowery and Hagen each did one of them).