This is an absolute treasure trove of primary sources from the first 1500 years of global Christian history. For anyone who wants to read these ancient texts directly (there's essentially no commentary from the editors/compilers - simply short paragraphs introducing the context of each piece) then this is your best entry point. I greatly appreciated the breadth and diversity of readings included - an effort is made to truly have a global scope, rather than centering the European church, and there are readings from thinkers that would eventually be deemed heretical by the mainstream church. These readings, in particular, really help to flesh out the debates that raged in the early centuries, and even lend some nuance and complexity to the heresies in question. This is essential stuff for having a deeper grasp on Christian history.
One consideration - the reading of this book is greatly enhanced if accompanied by some sort of narrative history, as that will place these primary readings firmly in their context (beyond the very short and simple paragraphs provided by Coakley/Sterk). I read this alongside Wilken's "The First Thousand Years" and Logan's "History of the Church in the Middle Ages." Other good options would be Gonzalez (Story of Christianity), Jenkins (Lost History of Christianity) or McGuckin (The Path of Christianity).
Bottom line - the understanding of our own faith is impoverished if we have no sense of our own history. This book is an invaluable resource towards building a richer historical perspective.