This book is a polemic, so the measure of it should be the extent to which it convinces. The case made is that enlightenment values represent the best way for human beings to order their societies, but that such values need to be actively defended. Society should not tolerate multiculturalism where it impinges on these core principles. Religion and totalitarianism are the main threats.
So far so good, but I felt the author understated the difficulties in handling the gray area where the exercise of free speech may lead to real harm (using the example of shouting "fire" in a crowded theatre). This led me on to some dissatisfaction with other aspects of the book where the author is asserting the direct applicability of enlightenment values today. In particular, I did not see many ideas about how you deal with the massive erosion of the right to privacy, given that the technological drivers for greater governmental intrusiveness are irreversible.
At its heart, the book gives quite an elitist assessment. The author notes the widespread sense that people are no longer interested in civil rights, but the real problem that is of concern is the loss of commitment among intellectuals. This section of the book is quite difficult to follow if, like me, you are not well-versed in political philosophy.
The author clearly makes the case that our rights in Britain should be better and more-formally protected. His take on the international dimension is much harder to accept as a political reality since, he seems to say that we have every reason to promote our values since they are objectively the best, but this should not be done (for example) in the manner of the invasion of Iraq.
Multilateral inter-governmentalism is the preferred route, with all its flaws. What is unclear is how or why this system should take on the values developed over the past two centuries in Europe and the US. The multilateral role becomes even more problematic because as the author himself notes, the UN Declaration of Human Rights contains both classic political rights and economic rights This latter group of rights considerably increase the ambition and scope of a rights-based approach and raise questions about economic governance and global redistribution of wealth which are dealt with in a rather cursory way