This volume is mostly a reprint of the manuscript mentioned in the title. Adam McLean gives some brief observations on the material and the manuscript's history then let's the user do the interpretation.
Why I call it invaluable is that it really constitutes one of the most important links between John Dee and the late 19th century schools of occult (i.e the Golden Dawn and the Aurum Solis). For those who, like myself, question the why's of the correspondeces formulated by the GD (esp. in terms of geomancy) this book unravels that mystery. While Rudd did not actually describe the specifics of his attributions, it becomes clear where the GD was borrowing from. It's catalog of spirits also contain entities from other Grimoire traditions and their associated sigils which probably make it useful for anyone investigating those traditions (e.g. Solomon).