This is mostly a picture book. It is in dictionary form, with three dictionaries, one each for Classical, Celtic, and Norse myths. Many of the illustrations are lavish and excellent, including oil paintings, museum pieces, and story-book illistrations circa 1900. Other illustrations (about a third) are meritless; evidently drawn to fill up space in the book.
The text covers major entries that could be found in any dictionary of mythology, but falls severely short on minor characters and places. It is also missing several obvious entries: for example 'dwarf' and 'giant' and 'troll' are missing from the Norse dictionary.
The Norse dictionary includes a smattering of characters from Baltic and Finnish (Kallevalla) mythology but it is even more incomplete than the Scandenavian entries.