It now appears that everyone knows and agrees: the show wasn't the same after Barney left and after it transitioned to color.

I tell ya, there’s just somethin’ about the town of Mayberry on The Andy Griffith Show that makes folks wanna slow down a bit ...

Andy Griffith, Don Knotts and Ron Howard circa 1965 ... although I do say that I don't think the color episodes are all that good. There's some good ones, but the thrill is gone, to paraphrase ...