The 2009 edition of the Writer's Market is much improved over the 2008 edition: the labelling has improved, so it’s far easier to navigate your way around the dense and thorough listings, and the associated website is now accessible to everyone, free of charge.
The articles in the guide are a real strong-point: there's a foreword from Joanne Harris, author of Chocolat, a piece about crime writing from Simon Brett, an article about writing for the internet by Scott Pack, Commercial Director of the publishing imprint The Friday Project, a piece about acquiring fiction by Penelope Hoare, Deputy Publisher of Chatto & Windus, and many other articles from editors, writers and agents. I would have liked to see more information about the mechanics of the publishing industry, and more specific information to help people spot scams and dubious practices for themselves—but that's not surprising, bearing in mind the subject of my blog!
My main reservation about writers' guides such as this one, and other similar guides such as the Writers' and Artists' Yearbook and the The Writer's Hand Book, has nothing to do with their content or design.
A novice writer recently told me that she knew that the publisher she'd submitted to was legitimate because it was included in both the Writer's Handbook and the Writers' and Artists' Yearbook. When it turned out that she had submitted to a vanity press she was hurt and upset, and felt doubly foolish having made such a public announcement of what she thought of at the time as a writing success. She made the common assumption that all entries were vetted in some way before being included in these guides, and she was wrong. When these books are compiled, entries are requested from all available sources. The replies are then collated into a book with little or no content-checking or verifying.
I'd like to see the editors of all writers' guides add a prominent warning that inclusion in their guide does not mean endorsement. Meanwhile, make sure you realise that while these guides are useful they are not a substitute for thorough research and careful fact-checking.