I was once at a book conference where an agent-turned-author was pitching her book on how to pitch a novel by giving out bad advice. One of the bad things she said was, "Subscribe to Publisher's Weekly." At this point everyone began furiously scribbling on their notepads like she was Moses on Har Sinai, but either that didn't result in one extra subscription or someone in the room had a lot of money to blow.
Publisher's Weekly is a trade publication for the book publishing industry. Being a "trade magazine" means it's mainly - or entirely, really - for people who work in the book publishing industry. With a small readership circle and little or no news stand sales, it makes its money back by advertising and by a $240/year subscription fee. Newsweek, another weekly of about the same length, costs me about $50 a year. On the other hand, Newsweek is not a trade publication, it's timely, and it has high sales from news stands.
I am very fortunate that my boss was having a good enough year last year that she finally broke down and subscribed. Some agents don't. Most editors rely on their office subscription. I once saw it in a magazine shop at Times Square for $14.00, which was $10.00 more than I was willing to pay. I don't get to read it every week, but if I'm in the day it comes in, I do get the privilege.
My G-d! There's an entire magazine out there of industry secrets?!? And it's hidden behind a huge price tag? Those bastards! Trying to keep the small author down.
In actuality, PW is what it is - a trade magazine. That means it discusses industry trends (read: not what kind of book you should be writing), produces more in-depth bestseller lists than the NY Times with some sales numbers, provides some information on comings-and-goings within the industry (so you can see who moved to what house, important if you know that editor), and generally provides a calender of major upcoming releases, book fairs, and other things of note. The opening pages are the articles, which are short but discuss topics relevant to the industry (Amazon's new policy of only dealing with Booksurge and no other POD publisher was this week's topic). Most of the rest of the magazine is just capsule reviews of every book that came out that week, most of which are available for free online and are generally favorable. The last page is something interesting (this week: the day in the life of a publicist) which is meant to get a few chuckles. Again, insider stuff, and we say that because, well, some associate editor taking a new position at Doubleday after leaving Scribner's is not all that important to your writing career. Focus on your writing, polish your query, and you should be fine.