Carney's a working journalist who is currently asking questions that other writers seem willing to ignore (chiefly, "Are freelance writers getting paid enough for their effort?").
This guide touches on that question, but is essentially an insider's guide to navigating the sometimes byzantine freelance world.
Thankfully, Carney assumes you can write; he doesn't embarrass himself (or us) with a lot of "How to write gooder" advice.
Instead, he focuses on the big picture concepts that are often overlooked by new writers. (You're far more likely to get assignments if you're the only writer in a news-rich area as opposed to a general assignment writer in New York.)
The online world is filled with dull, me-too articles about succeeding as a freelancer. Too many of these are written by stiffs who have only succeeded at the basement level of the industry, and their advice is typically obvious and lacks insight.
Carney avoids covering the same ground, and while his short (free!) guide is a little lacking in specifics (he does helpfully include several of his better pitch letters), the book still offers plenty of useful advice about making a living in the freelance writing universe.