Engraving on metal plates is not easy, and space on Nephi’s small plates was limited. So why would Nephi go to the tedious effort of copying a large amount of Isaiah’s writings into his record? He did it “that whoso … shall see these words may lift up their hearts and rejoice” (2 Nephi 11:8). In a sense, the invitation to read Isaiah’s writings is an invitation to rejoice. You can take delight, as Nephi did, in Isaiah’s prophecies about the gathering of Israel, the coming of the Messiah, and the millennial peace promised to the righteous. You can rejoice that even in a day of “trouble, and darkness,” you “have seen a great light” (2 Nephi 18:22; 19:2). You can rejoice that you can “draw water out of the wells of salvation” (2 Nephi 22:3). In other words, you can “rejoice in Christ” (2 Nephi 25:26).
Boyd K Packer explains in a talk titled, The Things of my soul, When you start reading the book of mormon, it’s fairly easy… “Then, just as you settle in to move comfortably along, you will meet a barrier. The style of the language changes to Old Testament prophecy style. For, interspersed in the narrative, are chapters reciting the prophecies of the Old Testament prophet Isaiah. They loom as a barrier, like a roadblock or a checkpoint beyond which the casual reader, one with idle curiosity, generally will not go.
You, too, may be tempted to stop there, but do not do it! Do not stop reading! Move forward through those difficult-to-understand chapters of Old Testament prophecy, even if you understand very little of it. Move on, if all you do is skim and merely glean an impression here and there. Move on, if all you do is look at the words. Soon you will emerge from those difficult chapters to the easier New Testament style which is characteristic of the rest of the Book of Mormon.
Because you are forewarned about that barrier, you will be able to surmount it and finish reading the book.”