I had this book recommended to me about 1.5 years ago as an introduction to the Arian Controversy. I bought it and tried to read it, but there was just too much information. He goes into great detail about each aspect of the debate, including theological background, examination of primary sources, history of interpretation, questions of authorship and dating, and details on all the major and many of the minor players. I got bogged down and frustrated. A year and a half later, having read Barnes's books and examined some of the primary documents, as well as getting a better idea of the course of the controversy, I now find the book very useful for reference, and can read through a chapter without feeling like I'm drowning.
I would not encourage you to refrain from buying this book, but I would encourage those new to the Arian controversy to try and find something shorter and more manageable for an introduction. Get your bearings on the major councils, bishops, theological camps, and writings of the controversy. If you're not sure where Athanasius was bishop, you definitely don't want to read this book yet. If you're not sure what the Council of Serdica was you still might want to hold off. If you know who Constantius was and what theological position he favored, you probably have the background needed to wade through this rather lengthy book. I found that once I knew the general chronology of Athanasius' life fairly well, it served as a good hook to hang all this information on - and it is a lot of information.