Commentaries represent the two-edged sword of Bible study, so to speak. There is the potential for great benefit or great harm from their use or misuse.
Commentaries can be very helpful when used properly. They can help present parallel Scriptures to what is under discussion, can provide insights from our knowledge of history and culture, and sometimes can present interpretations that are more consistent with the rest of the Scriptures than what we considered on our own.
On the other hand, commentaries are written by men and often espouse the doctrines of men. Not a few commentators have used their commentaries as a means of proclaiming their deviant doctrines.
Commentaries can be good– but always be watchful!