I wanted a book to help me get more psychologically comfortable with oral sex, and this book was great to do just that!
If you (especially if you're a woman, I feel) are into oral sex but have some baggage I feel this book does a great job addressing oral sex on men in ways that other books tend to avoid or just exclude (like "Passionista," by Ian Kerner who wrote "She Comes First," did not, nor is it addressed in "The Guide To Getting It On."). Anything like emotional/psychological hesitancy to get too involved because of the power-exchange that happens, or that it feels anti-feminist, or you're afraid of him pushing your head down, etc. is TOTALLY addressed!
Violet's book also covers way more things, like the best positions to go down on a man in, deep-throating, variety of positions, what to do when your jaw/mouth gets sore, etc. I found that even though my partner didn't think I needed to brush up on my going-down, it definitely helped me feel more comfortable with the social stigmas placed on women giving head, and more comfortable with my abilities!
Highly recommended! (I'd say buy a paper/hard-copy, not an e-book, so you can flip through it for easy reference.)