Barnett's interviews are with artists who get bypassed in the press again and again, from the late Odetta to Nona Hendryx to Joan Armatrading to Angelique Kidjo. A few are known for their singing more than their writing (Dionne Warwick, Shemekia Copeland, Dianne Reeves), but most of the chapters are insightful about how these women create songs or what inspires them about the music they tackle as interpreters.
To find anything recent about the late Nina Simone is rare enough, but this is a fabulous chat (ranging from pithy to downright scalding) with her on top of that. It's interesting that Simone loathed Rap, while some of the younger women interviewed in this book love it.
I think it was Pamela Means who said that she only heard one Lucinda Williams album, didn't care for it, and never checked out Williams' work again, showing what a small window of opportunity most artists, female or otherwise, are afforded in our slam-bang culture. We've got many types of bigotry to deal with, not to mention our collective short attention span, and "I Got Thunder" takes on these issues--it's impressive.