I am currently 25 years old and I have been using emails, computers and internet since I was 13. So unfortunately there is nothing new that this book poses that I don't already know. However, I do find that for people that have never (or very little) used emails in the past this book will give a good insight into how to have good email etiquette. For example, I would recommend this book to two particular groups of people: the currently rising generation and people who have refrain from trying out the technology (my parents will be in this category). As an optional group, I'll recommend the book to anyone who wants to simply brush up on their etiquette, without expecting to learn something new.
There are two good sections at the end of the book, that for those who might see them acronyms and emoticons being used but don't necessarily recognizes them is worth to look over. These sections are by no means comprehensive, but they are enough to cover the basics, one is a list of acronyms (LOL, BRB, etc.) and what they stand for; the other is a list of smiley faces and the emotions they represent.
As a side note, I think someone skipped a section when editing Email Etiquette: Netiquette for the Information Age
because the grammatical errors that I found -although a few- were too close together. For example, "relpied" instead of "replied" and "seach" instead of "search".