The King James ONLY Movement (KJV Onlyists)

The King James Only movement asserts that the King James Version (KJV) of the Bible is superior to all other translations of the Bible. Adherents of the King James Only movement believe that the KJV is the greatest English translation ever produced, needing no further improvements, and they also believe that all other English translations which were produced after the KJV are corrupt. Is this true?