I read the book and imperfectly tried with my son from about 3 days old to 6 months. He would hold his breath. However, I found the
www.uswim.com website to have easier to understand and implement instructions. At age 2 he will hold his breath for about 3-5 seconds, but can't really swim, but he can back float.
I also used the Doman book with my daughter starting at about age 1 and again imperfect implementation until age two. She would not hold her breath. At age 3 I discovered the uswim. And by age 4 she had completed level 2 and was into the second skill on level 3. I put her into a conventional RedCross swimming lesson this summer and she passed level 2 (designed for 6-8 year olds) at age 4.
The Doman book has general knowledge but I find it lacks on details of how to implement. If you can get the book for free, then I would read it, if I had to buy the book, I would save my money and use the free resources on the Internet.
Pokerdads's blog has some great suggestions on swimming. And an excellent post on helping the parent get over th fear of your baby being underwater.
Happy swimming.