Although this book overpromises, it's still a fine canter down the path which brought us to where we are today in terms of freedom of thought, speech and a few others.
If you are looking for detailed analysis, or balanced history then this book is likely to disappoint - it would be a rare feat to capture 500 years of nuanced development in 300 pages. Similarly, despite the author's reputation as a fine thinker, the quality of the prose leaves a great deal to be desired and an impression, frankly, of something finished in a hurry.
However, it's best to take this for what it is, which is a relatively readable review of some of the first, and hence most significant, steps on the long road to the position we enjoy today where we are able to take many of our freedoms for granted. For example, few can fail to be inspired by the example of Sebastian Castellion, who may have been the first to debate publicly whether it was a good idea to burn heretics. Similarly, it helps frame the context and significance of a number of key thinkers including Milton and Locke, albeit without any great discussion of their views.
For anyone looking for a thought provoking and accessible entry to the history of political freedoms and ideas, then Towards the Light (at least the first 2/3) may be just the library ticket.