Tolkien's writings have been one of my chief hobbies for years (http://tolkien.slimy.com/), so I've been really curious about what this new book would be and how it would be received. Having read a fair bit about it and skimmed through the 30-ish pages available for preview on Amazon... I'm still not sure. To explain that, I'll start with some background.

The previously available books by Tolkien (many edited by his son Christopher) took different forms: The Hobbit and The Lord of the Rings are traditional narrative stories; The Silmarillion blurs together the styles of the Bible, a history textbook, and historical fiction; Unfinished Tales is a collection of isolated or incomplete stories and essays along with framing commentary for each; and the twelve History of Middle-earth books are a thoroughly scholarly analysis of the complete textual history of Tolkien's invented world (which happen to include quite a lot of fascinating and enjoyable stories and fragments along the way). Christopher Tolkien has done a really admirable job of sharing his father's broader vision (at his father's request!) with as wide an audience as possible.

When The Children of Húrin appeared (around 10 years ago), it was the first self-contained narrative story about Middle-earth published since Tolkien's death. Most or all of the actual text had been published before (it's a very close match to the first story in Unfinished Tales), but it was framed in a way to be much more accessible: it's quite readable by someone who hasn't read anything beyond The Lord of the Rings, with no Silmarillion necessary. (I wrote a short "bridge" of backstory to help with that, for people intimidated by the book's 15 pages of introductory information: http://tolkien.slimy.com/essays/HurinBridge.html) My sense is that this book did a great job of opening some of Tolkien's broader vision to a wider audience. (And people who enjoy it might go on to read Unfinished Tales or The Silmarillion with a bit more interest.)

From what I can tell so far, Beren and Lúthien is a very different beast. It's not a single, coherent narrative, but rather a focused "slice" of textual history from throughout the whole History of Middle-earth series. The style of Christopher Tolkien's commentary seems to be more conversational and less scholarly, but it starts with the earliest version of the story (which feels very foreign to readers of The Silmarillion) and talks through its stages of evolution, evidently including its lengthy rendition as an epic poem.

So I'm not really sure what audience this is for. My sense is that it's written to be accessible to people who have only read The Lord of the Rings, and it tells what is perhaps the most central story of the First Age of Middle-earth. That's very appealing! But the way in which it's presented here means that it will primarily be enjoyable to people who have a fair amount of interest in Tolkien's writing process and in keeping track of the many, many shifting names and plot lines in the story as it evolved over five decades or so. (And how many people with that interest haven't already read all of this material in its full context in the History of Middle-earth books anyway?) Maybe it can serve a useful role as a bridge between the Silmarillion/Unfinished Tales reading experience and the History of Middle-earth reading experience? Or maybe there really is a community of textual history fans who don't have the patience or interest to read a book like The Silmarillion? I'm very interested to hear what experiences different people have with the book, and I should probably read it myself to get a better sense of what it can be.