Good idea --- useful, valuable
This book has been planned as a text book for music academies.
Just after opening the cover, I found it quite useful for music lovers in general, and valuable for serious ones --- especially players of any instruments, both professional and amateur, and listeners as well.
This book can nourish not only the knowledge of musical styles, but also of historical aspect of music.
If you want to know music deeper, and then, more enjoyable, one of the solutions would be this one.