How-to-write books are such a hit-or-miss proposition, and what is useful to one person may be useless to another. For example, I'm probably the biggest S. King fan that you'd find outside of the basement-dwelling community, and 'On Writing' is probably the most frequently recommended book on the topic today, but I felt it offered me very little in the way of practical tools which I could apply directly to my work. (It is, however, a fascinating memoir of the creative process and a very rewarding read as such...Go get it now; you won't regret it.)
Rock Your Plot, on the other hand, actually gave me the "tools" I was seeking to fill up my toolbox: how to create a solid three-act structure, pace the action, and plan the plot points. This book enabled me to get out an old project, re-plot it from scratch, and improve it tenfold. The thing may never rate publication, but it's a much better unpublished MS!
Most people want to believe that writing is an organic process and that, as King says, we should just find an interesting image and let the story unfold itself from there. In this model, the plot grows like a plant, of its own accord, while the writer/gardener prunes and waters but is essentially a bystander to the process. And that's fine if you're Stephen King. If you're a plain-old peasant like me, though, you wind up with a lot of overgrown weeds and brambles.
Rock Your Plot's paradigm is more like architecture than horticulture. Here, the writer draws up the blueprints first, then lays the foundations, and only then begins to build. It's planning a towerblock rather than planting a tree.
So give this book a shot even if you are a little in love with the "gardening" model of writing. You'll be surprised at how much of the craft _can_ be learned, and at this price, what do you have to lose?