I was required to complete an essay on the distinction between positive and negative freedom for part of my degree, and whilst researching in the library, I came upon Nigel Warburton's "Freedom".
I found the book immensely helpful, as it was up to date with current issues and controversies, and contained a lot of easy to understand, pertinent examples. Many political science texts are quite difficult to grasp, because the authors use complex, technical terminology. However, Warburton writes in a relaxed style, which is casual without "dumbing down" the issues.
I especially liked the way that he focused on specific passages of each author's work, then interpreted them in his own words. It was also good that he included the full readings (for instance, Charles Taylor's article) at the back so that readers who wished to gain a more in-depth understanding of the original text could do so.
The questions within each chapter encouraged the reader to actively engage with the text, and it was handy that answers were provided to see if you were on the right track.
Although I believe this book would be best suited to students, anyone with an interest in the issues surrounding freedom and its applications will find it a great help.