So, as I noted yesterday, the Chris Mitchell memorial volume was one of two books to arrive together, the other being John Carswell's TOLKIEN'S REQUIEM: CONCERNING BEREN AND LUTHIEN. At just seventy-four pages, this is more a chapbook than a book, but then there's a long tradition of chapbooks in Tolkien studies, going back to the legended days of T.-K. Graphics (of which I still have two or three on my shelves).
This particular effort summarizes the story of Beren and Luthien and discusses how it works out various themes Tolkien considered important. It has a few minor glitches (Huan is not a "mighty wolf-beast" and Beleriand does not lie east of the Blue Mountains) but they don't affect the argument.
The only real problem with this book is one of audience. Carswell looks only at the legend as it appears in THE SILMARILLION, not at the many other versions Tolkien wrote of it. But anyone who's likely to buy a book like this on a specialized aspect of Tolkien studies like this is likely to have already read THE SILMARILLION on his or her own, in which case he or she wdn't need this entry-level introduction. It reminds me of the late great Paul Kocher, whose second book* basically told the reader what happened in THE SILMARILLION. But anyone picking up Kocher's book was likely to have already read THE SILMARILLION and been looking for something that went deeper than just telling them what they'd already know. A book like A SKELETON KEY TO FINNEGANS WAKE is helpful because Joyce's FINNEGANS WAKE is (deliberately) incomprehensible at first reading; whereas the difficulty of reading Tolkien's THE SILMARILLION was largely limited to the need to keep track of a lot of very similar names and was much exaggerated by professional book reviewers of the time.
Carswell may be fortunate in one thing: the forthcoming publication of Christopher Tolkien's edition of the Beren & Luthien story may attract readers to his little book that wd otherwise have overlooked it.
*Kocher's first book, MASTER OF MIDDLE EARTH, was the best of all the early (pre-Carpenter) books on Tolkien and I'd still rank it in the top ten even today.