We know very little of Emer, but we know enough to realize that he was a great man. He had been a righteous king, much like king Benjamin would be to a later people. He had even seen God. This makes him great by association for it puts him in the same class with some great prophets including: the brother of Jared, Nephi, Jacob, Alma, Mormon, and Moroni.
“The experiences of Emer are some of the most promising moments in these chapters of rampant wickedness among the Jaredites. As a very righteous leader of his people, Emer was privileged to have the veil parted and see the Lord Himself…Moroni may have desired to show us through Emer that not only righteousness but perfect faith is possible in a world sandwiched in on all sides by wickedness.” (Frank F. Judd, Jr., Book of Mormon Symposium Series, 4 Nephi - Moroni, edited by PR Cheesman, MS Nyman, and CD Tate, Jr., 1988, p. 150)