One time, after presenting some of this material in a fireside format, one listener said, "I still don't see what's so great about Isaiah." I was quite taken back by the question, and I didn't know what to say. I thought to myself: If Jesus said "Great are the words of Isaiah," then they're great. It's our job to find out why.
Since then, I've done a little thinking about how I might answer that question if it ever comes up again. Here's how I might respond today.
Isaiah's Form: Isaiah's words are great because of Isaiah's form. Isaiah was a master of the Hebrew language. As Victor L. Ludlow has observed, Isaiah worked in Hebrew the way Shakespeare worked in English and Goethe in German (see Unlocking Isaiah in the Book of Mormon, 4). Most of us can't read Hebrew, but even after going through King James' translators and being turned into English, Isaiah's language strikes us as expressive and beautiful: "And his name shall be called, Wonderful, Counselor, The Mighty God, The Everlasting Father, The Prince of Peace" (2 Nephi 19:6; Isaiah 9:6).
Isaiah's Span: Isaiah's words are great because they cover from the beginning to the end and everything in between. We hear echoes from the premortal existence in his words, "How art thou fallen from heaven, O Lucifer, son of the morning!" (2 Nephi 24:12), and descriptions of things yet to come in the millennial day: "The wolf also shall dwell with the lamb, and the leopard shall lie down with the kid . . . and a little child shall lead them" (2 Nephi 21:6). Isaiah, as did many other prophets, saw everything from the beginning to the end, and wove his narrative together in remarkable and memorable ways.
Isaiah's Detail: Isaiah could, in one verse, prophecy two or more events. For example, while speaking of the "Current Event" of the pending attack by the Assyrian army, he could word it in such a way that it would also speak of the "Coming Event" of the latter-day gathering: "And he will lift up an ensign to the nations from far, and will hiss unto them from the end of the earth; and behold, they shall come with speed swiftly" (2 Nephi 15:26). He did this sort of thing with exceptional skill in a number of places, allowing for multiple interpretations of his words. Brother Robert J. Matthews refers to these as "pattern prophecies," which can encompass events in different ages and among different people but still fit a pattern.
Isaiah's Testimony: Isaiah saw the Lord and, in humility, declared, "I am undone." An angel touched a burning coal to Isaiah's lips and purged his sins. Then Isaiah offered his "Here am I; send me" as an example of consecration to all of us who have received the testimony of Christ and received his forgiveness. This remarkable account of Isaiah's cleansing and calling by the Lord certainly qualifies as "great."
The resurrected Lord put his own endorsement on Isaiah's words when he said, "And all things that he spake have been and shall be, even according to the words which he spake" (3 Nephi 23:3).