You know what one of the great things is for Tolkien fans? Despite it only being forty years since the Professor's departed this world, we already have a great deal of his writings in publication. This past year, I was reveling in all the Charlotte Brontë writings that had been published only in fairly recent years, even though she died over a century before Tolkien did.
So while things like The Legend of Sigurd and Gudrún may not always appeal to the casual reader, for a hardcore fan or semi-scholar, they're treasures. This is apparent simply in the way that The Fall of Arthur, published earlier this year, is put together. Although the unfinished poem is only forty slim pages, the book is a hardcover filled with commentary on the poem's writing, context, and meaning. In these writings, Christopher Tolkien not only describes when Tolkien was working on this poem and such, but also how it relates to his Middle-earth writings. Note that I did not read all of this commentary, only glanced through it. I'll save a more thorough reading for later.
For myself, the value I gained was in connecting imagery and language to Middle-earth. Although this poem concerns the world of King Arthur, that subject material is not wholly unlike Tolkien's own legends. There is still much imagery of Nature and its power and beauty. The flow of poetry, rich but not heavy with alliteration, is reminiscent of the poetry that fills the pages of The Lord of the Rings. What scholarly treasures the Tolkienians continue receiving.