Seeing that much of the material on Lather has been previously released on four separate Zappa albums during the late 70's, this 3CD set can be viewed as more of a "Best of Zappa 1976 - 1981" rather than a complete  album, as it was intended to be.  Despite this, even if you do own those  four albums ("Zappa In New York" and the Warner Brothers  trilogy), it is well worth acquiring Lather for the monster that it is.