I gave this book and its techniques a really good try, had fun along the way, but ultimately didn't succeed.
I did all the exercises, I practiced assiduously for about two months, I read the book carefully cover-to-cover at least twice. I had many enjoyable sessions along the way, and the very idea of striving for multiples turns me on. But try as might, I couldn't achieve multiple climaxes.
I first tried Matak Chia's techniques, which are similar but have a disturbingly quasi-religious aspect.
Both Keesling and Chia have this in common: they imply that if you fail, it's because you didn't try hard enough, didn't read carefully enough, etc. I've not met anyone who succeeded (how would I?) and if I did, how could I tell if they were truthful?
I'd still recommend the book for the turn-on and the sensitizing exercises. Just approach with open eyes.