This isn’t quite an atlas in the sense of containing maps, unless you take it a bit more metaphorically to be a sort of field guide to Middle-Earth. If you’re a big fan of Tolkien, you probably don’t need to read this for itself, as it just summarises and teases info from the books, but if The Silmarillion is too heavy for you, it might help you through. It’s also just a gorgeous book: lots of illustrations, lovely binding, etc, etc.
Less of a book to read and more for reference — and a good taster of various artists who’ve done work in Tolkien’s universe. I’m going to have to look some of these up, and maybe even try and get a couple of prints.