I find the Companion Bible to a precious help in word studies and accurate interpretation. On a personal note, I don't agree on all of Bullinger's doctrinal positions but that's OK and easy to separate from the study of the text. This Bible is a rich treasure of technical considerations of renderings from the original languages. It is honest when acknowledging the few errors in the KJV, and over all, extremely accurate. It is a work of man and not completely without some error, but these are small and insignificant to the work as a whole. The errors are not related to the original text of the KJV 1611. This is a highly technical work alongside of the KJV for any serious student of God's Word.