I listened to the audiobook version of this, but I think I'd recommend going for the print version. First, because Erik Davis's occasionally florid rock-journalist prose sometimes sounds a little odd being read aloud. (Especially since every time the reader says oeuvre, mese en scene, or avant la lettre, I flinch. I'm not necessarily going to defend Davis's constant use of French expressions, but given that he did it, they should have gotten a reader who could pronounce French.)
Secondly, the straightforward audio adaptation that Audible did of this book strikes me as a missed opportunity. It would have benefitted tremendously from having short illustrative snippets of the music under discussion being played at appropriate moments.
At any rate, the book takes the interesting tactic of analyzing Led Zeppelin IV as if it is a narrative, which each song representing a different stage of the hero's journey. While I think this probably exaggerates the coherence of Led Zeppelin IV (which is not, after all, a concept album), it does provide an engaging way of pointing out thematic connections and recurring tropes in the songs.
The book spends roughly two-thirds of its time discussing lyrical themes and the overall Zeppelin "mythos", and only about a third of its time discussing musical elements and details of song recording and production. I'd personally have preferred it if that ratio had been flipped, but probably the ratio is right for the general reader who didn't spend a good chunk of her teenage years trying to learn the guitar parts to at least half the songs on Led Zeppelin IV. Also, if you've read Hammer of the Gods or any other Led Zeppelin biography, you'll be familiar with a lot of the basic biographical details the book covers.
Still, I learned some new things from the book, and it would probably be the perfect introduction for someone not already steeped in Zep lore or who wants to get a sense of what all the fuss was about.
Finally, I'll be forever indebted to the author for his description of listening to a Led Zeppelin album being like, "opening the doors on a raunchy Arthurian advent calendar." What an image.