This book has definitely enriched my understanding of Sen and Nussbaum's Capability Approach with its considerations about functionings being secure or insecure for persons. Before this book, it was rarely addressed that the Capabilities Approach needed to sustain functionings for persons; such a notion was merely assumed but never justified. What Wolff and De-Shalit bring to the table is this: that such capabilities should allow persons to reach certain functionings in a society and persons should be able to sustain functionings for long periods of time without unnecessarily risking them by being placed in 'forced' situations. If persons must place themselves in predicaments that endanger their functionings more so than others, then it is evident they are disadvantaged.
The examples in this book were accessible and the book has an overall feel to it that can be appreciated by both a casual reader and an academic reader. The book reads like a progressive narrative with a "plot" or main idea of what it means to be disadvantaged, problematizing disadvantage, then reaching a "climax" where some solutions are suggested in trying to address issues of functionings being insecure due to not so carefully planned public policies, which later on Wolff and De-Shalit argue, should become inhumane and never be legislated. Though later on in the book, Wolff and De-Shalit give careful attention that fertile functionings are not known as well by policymakers as corrosive disadvantage.
The strategy and argumentation in the book is also noteworthy. Wolff and De-Shalit commit to argue the existence of what they call fertile functioning and corrosive disadvantage where acquisition of some functionings naturally lead to other functionings while some insecurity of functionings cause loss or risk of loss to other functionings. The major thrust in their argument is this: prove the existence of these fertile functionings and corrosive disadvantages and society/government cannot help but to agree with their existence. Let their existence influence public policy where society will ensure that only fertile functionings are promoted.
If you're looking for a book that has concrete, exact, universal answers for legislation, you will be disappointed because it is not that kind of book. It is more a book that evokes persuasion to accept the existence of disadvantage, then through justification, show that disadvantage should not be perpetuated by public policies.
This book has influenced the work of Martha Nussbaum in her new book Creating Capabilities. But ultimately I feel that reading this book has given me more respect for Nussbaum's book because I read Nussbaum's book initially expecting witty suggestions to create specific laws that would universally transcend cultural norms. Instead, Wolff and De-Shalit have shown me that the best way for democratic liberalism and policy change to take place is to simply prove the existence of injustices and benefits to society, then with education of these existential claims, legislators cannot help but to make laws that conform to this justification. Wolff and De-Shalit's strategy was the same as Nussbaum's and I find merit in this form of argumentation now. Great work and I hope to see this discourse continue in future books and conferences.