This was an interlibrary loan book, and I didn't have time to read every annotation before sending it back, but I read enough to rate it. It certainly seems thorough. Every text variant among editions is given. I was most interested in the historical bits - writers that may have inspired the Hobbit, etc. It also includes illustrations from multiple editions, though I would have liked to have seen all of an illustrator's work together rather than hunt them down spread throughout the work.