Well kinda, they were on and off. The way I see it, the Korn timeline was like
S/T - Great
Life Is Peachy - Great
Follow The Leader - Not so good
Issues - Great
(Queen of the Damned Soundtrack - Great)
Untouchables - Poor
Take A Look In The Mirror - Poor
Greatest Hits - Predictable, and very poor 'new' material.
At their height they were more than just okay.