Very nice. I have a book of maps for his world on a bookshelf here which I got when I was young (The Atlas of Middle-Earth - https://en.wikipedia.org/wiki/The_Atlas_of_Middle-earth). I enjoyed reading that a lot, and it was nice to see that most parts of it are well thought through and internally consistent (there's one piece near Rivendell which is a bit of a mess between the Hobbit and LotR but we can let Tolkien have one minor issue).
I have that same book. It was a major source of inspiration when I was a kid.
This book is amazing; the fact that she was able to work out most everything involving geology just from Tolkien's descriptions is wonderful.