This is a collection of early Christian apocrypha and pseudepigrapha, such as the "Acts of Paul and Thecla," the "Protevangelion of James," and the like, also including the "Apostolic Fathers," namely the letters of Clement of Rome (c. 96 CE), Ignatius of Antioch (d. 113 CE), and Polcarp of Smyrna (c. 113 CE for his letter; d. circa 150 CE). These texts, written for the most part in the ante-Nicene period, are of tremendous importance for the understanding of the development of the Christian movement and its theology, ethics, practice, and relationship with the surrounding society. I recommend to all my students that they familiarize themselves with this literature.
However, these texts were NEVER part of the "original" New Testament, if such a thing could even be said to have existed prior to the 4th c. CE. They were never "forbidden," either. The letters of Polycarp, Clement, and Ignatius, together with the apocalypse known as the "Shepherd of Hermas," were read and valued in the early church. They were never "excluded" from the New Testament, for the simple reason that they were never "included" in the first place. It is true that some reading communities accorded some of these books equal or near-equal status with the NT (for example, Codex Sinaiticus contains both Hermas and the Epistle of Barnabas after the books of the New Testament), but this was not the common practice of the majority of churches, and so did not become standard. The author of the preface writes in a misleading, sensationalist tone, suggesting some grand conspiracy theory to suppress these texts. This is a gross misrepresentation of the historical process of canon-formation.
The absence of a table of contents with links to the starts of each text is a serious drawback -- but it's also a free download, so who am I to be picky?