Anyone tried this?
I bought a 1 year subscription for around $20, and I have been happy with it so far. The online version is cheaper than the book and it's updated constantly.
It allows you to search through a large, complete, and constantly updated database for fiction and nonfiction markets. It found some markets for me that I never knew about. It is missing a few markets that I had found elsewhere, so I wouldn't rely on it as your only source.
You can personalize things, like create Favorites lists of markets you want to keep tabs on.
It also has a simple submission tracker. You enter your story, select a market from their database or from your favorites (or add a new one), put a date on it, and submit. You can see at a glance where your stories are and where they've been.
Subscription also gives you access to their library of articles. Some are very interesting, like the interviews with editors and agents.