Without having read the book in question, I feel this advice is good but partial. A lot of what he mentions in this post is mirrored in Dale Carnegie's "How to Win Friends and Influence People". I feel that Carnegie goes much more in depth than this blog summary.

One thing: the deli example he gives makes it seem (whether on purpose or not) that you should just say the words to get what you want rather than to actually care about what the other person is saying. You aren't trying to manipulate the other person; instead you should sympathize with them. I personally prefer this attitude change rather than a strictly behavioral change.