This book has two main virtues, in my opinion. First, it organizes its treatment of a wide variety of issues around a single theme, the philosophy of time. This subject is of perennial interest to philosophers, of course, and the authors highlight the many ways it intersects with the other great metaphysical questions, such as personal identity, free will, and God. Second, it packs a lot of information into a very small space. It contains dense, but lucid, discussions of the A-series and B-series, relational and substantival theories of time, countable and uncountable infinities, endurantism and perdurantism, and the Special and General Theories of Relativity.
I think this book will be somewhat difficult for the introductory reader, but I suppose that comes with the territory. Metaphysics is just hard! The dialogue format does little to alleviate this; in fact, the dialogues are often stilted and sometimes distracting. However, the advantage of this format is that it allows the authors to discuss the various sides of each issue without telling the reader which side to accept. There is a lot of metaphysics in this book, explained clearly and directly. Read it through or keep it on hand as a reference. Either way, I think a careful study of it (especially Part I) will pay off.