Cohn's book, as the title suggests, is firmly aimed at the Agile development end of the market. The book contains much useful material that is otherwise scattered throughout the literature - and material that a casual reader would not expect to find in a book on agile development techniques, so the book becomes worth reading for practitioners of all project sizes.
For example, there is a complete chapter on the prioritisation of requirements by desirability using Kano analysis. This technique divides requirements into three groups: - Essentials - those requirements that are essential for the stakeholder to even consider using it; - Linears - those requirements that are linearly valuable, ie those where doubling an element of the requirement is perceived as being twice as desirable; - Delighters - those requirements that delight a stakeholder - usually only a small number being necessary.
The author describes techniques to draw up a questionnaire based on Kano analysis for potential customers to quantify which requirements they categorise into the three categories above. This will also business stakeholders (such as product managers) to prioritise requirements. Cohn has a whole chapter on financial prioritisation - techniques that allow the quantitative financial measures be associated with requirements. The measures discussed are: cost (retained revenue, operational efficiencies and net cash flow), net present value, return on investment and discounted payback period. Armed with this information, business stakeholders are able to prioritise the requirements more easily. In addition, this sort of information adds credibility in the eyes of the CFO, who may otherwise remain unconvinced of the benefits of Agile projects.
In addition, Cohn devotes part of the book to estimating buffer size - something that is often missed in agile projects. He deals with both feature and time buffers and the best time to use each - or a combination of both.
The book becomes a "best buy" for all with its in-depth, readable treatment of topics that are rarely seen in a software development book.