Koomey's book "Turning Numbers into Knowledge" is definitely far more concerned about the process of analyzing data and presenting data than it is about mastering the art of problem solving. That is, Koomey does a fine job drawing together topics on research, analyzing data, presenting data, and introductory critical thinking skills. However, those looking for heuristics to use as approaches to solving problems will not find any here (at least not in the strict sense of, say, something like those found in works by Gyorgy Polya--though props must be given to Koomey for at least mentioning Polya).
For what this books does provide, Koomey does a not only a very nice job of presenting the his techniques and information, but it is also an incredibly well-written book. Koomey does provide both good and bad examples and explains how they contrast and what makes the good examples effective. There is some repetition relevant to certain principles Koomey is trying to reinforce throughout the book, and while I understand the purpose of such reinforcement, I did find it tiresome at times. Also, no statistical methods or rigorous mathematical examples are covered; these are left to other books, I suppose. That is, anyone looking for something akin to what they would find in a statistical "Design of Experiments" class will not find any such treatment here.
Overall, though, Koomey's book is a good one in that it does provide some business-esque (read: math-lite) approach to data analysis, and it does focus on the general craft of data analysis and presentation. It aims to being an introduction with breadth, and it does this nicely. There is an extensive "Further Reading" section for those that wish to peruse other sources Koomey uses and references.