This has to be one of the best books on popular music I've ever read. Werner's knowledge is encyclopedic and his reach expansive -- he covers the performers I'd expect him to cover, and connects them to other musicians and writers in ways I wouldn't have anticipated. Every few pages I felt the impulse to explore some new piece of music he'd just dissected, or revisit a well-known piece from a fresh perspective he'd just given me. He provides excellent historical and social context for the musical analysis, and each of the 64 chapters gets its own Notes section in the back. Each of the five sections also gets its own Playlist, which is going to keep me busy for years to come.
Particularly strong chapters included the ones on the birth of Southern Soul, Hendrix and the sound of Vietnam, Curtis Mayfield, the (Republican) Southern Strategy, Wattstax, P-Funk, and OutKast and the Dirty South, although every chapter is solid.
There are a few flaws, but no showstoppers. At times it seems like he's trying a bit too hard to shoehorn the evidence into his framework of Gospel Impulse/Blues Impulse/Jazz Impulse/Call & Response, but given that he got props from Bruce Springsteen after a show for identifying those impulses in The Boss's music, I'm going to defer to the dude's expertise.
He's on slightly less solid ground with the punks, overlooking the funk in for instance The Contortions/James Chance/James White, Teenage Jesus and the Jerks, Bush Tetras, etc, as well as not mentioning pioneering reggae punks Bad Brains. But it's true that most of the punk/early postpunk bands influenced by black music were British (Gang of Four, Slits, Mekons, Au Pairs, A Certain Ratio), and may have fallen outside the scope of his argument. He does cover the Clash pretty accurately.
Anyway, go read this now.