It is a fantastic tool when used in moderation.......when used to the extent it is in today's pop music it is truly awful...makes everybody sound like they use the same ROBOT voice as Stephen Hawking. If folk sound the same and there is no light and shade or any natural inflections or accentuation or emotion in the voice...then we can only presume that none of today's singers are capable of singing in tune or putting in a performance demonstrating such vocal aptitudes.
I see little point in wasting time using such a device if there is little or no audible difference in the end result