I read the book a long time ago, sometime in the 90's. I enjoyed it then, but I would think it must be kind of dated by now. As best I recall it, it tried to describe the process of rational drug discovery based on working backwards from the structure of the target. That was a relatively novel idea at the time, but is much more common now.
If you are interested in popular books on drug development, I think the book about Gleevec is a better read: