This is essential reading for anyone interested in how The Hobbit developed as Tolkien wrote and re-wrote it. It includes the early drafts, and, particularly importantly, Tolkien's very late and unpublished attempt to re-write it more or less in the style of The Lord of the Rings. He was probably right to abandon this: as far as it goes, it does lose some of the special individuality of the earlier book. But it is very suggestive of what he might have done with the later and more serious episodes of the story, if he had got that far.
Rateliff writes well, and his comments are usually illuminating and only occasionally pedestrian. This is obviously not a book (or rather, two books) for someone simply wanting to read the story. But for those of us interested in how these works came into being, and what they led to, it is a fundamental piece of scholarship.