If you're going to run a mythic campaign in the near future, then this book is a must. If you're a player, beg your DM to buy this book so that you can have some fun with the extra selections that this book gives you so that you won't have to get stuck with the few spells from Mythic core.
Content wise, the book delivers its promise. All core spells (if I'm not missing any) had been given a mythic version. Though some spells remain relatively circumstantial, there are some that you must simply pick because they're awesome. But the best thing is that even cantrips and orisons had been "mythified". Organization wise the book is quite thorough, providing general Mythic spell list with page numbers by class, by domains and bloodlines.
Bookmarks are available for the PDF and it's quite extensive... but stopped being extensive when it comes to the spell descriptions (didn't provide bookmarks for spell description in alphabetical order - in fact, it lacks one). Certain artworks are seemingly out of place, but they are of high quality nonetheless (especially the paladin on the same page with Mythic Miracle).
It's slightly on the high end price wise, but if you're going to run a mythic game then you might as well get Mythic Magic to open up choices for Mythic spellcasters. It's going to be fun for both ends.
Good work, Legendary Games!
Note: This review is made after the revision on 21/9/2013: after removing "unclear wording" and adding Mythic Permanency.
