1. It is a resource of quotes, for the most part. So, it's not like a typical commentary, where you can read the passage of Scripture, then read the "commentary" and have an idea of what's being said. This book is full of quotes (a few lines long) related to each passage.
2. Which leads me to the second point... Usually, when you have a commentary you know the author's bias-- whether he/she is conservative, liberal, their theological leanings, etc., and you can make like adjustments when reading. Not so here. You will need to be somewhat versed in Church History (or have access to a book) in order to distinguish the sound theology of these individuals from the not-so-sound/heretical theology. And, it's possible (as was the case with Origen, for instance) that some of what they say is sound and some is way, way off... You just need to have some tool to make that distinction.
3. This book is very helpful, nonetheless, because we often forget that the ancient Christians struggled with the essentials doctrines of the faith for hundreds of years... and were versed in Scripture (although some of them get lost in allegory, etc.). It is both helpful-- and respectful-- I think, to know what these fore-runners in the faith said.
Buy the book-- but only if you already have some other commentaries (or resources) you can consult.
I would advise anyone who finds modern biblical scholarship unhelpful to immerse himself in the Fathers directly and in the original context. If we then read the scriptures adopting, if only for the moment, their mindset, their presuppositions, and their methods, the scriptures will be openned up to us in a new and fruitful way.
We moderns can find allegorical interpretation, for example, somewhat farfetched. But it is clear to me that some of what the apostles intended to teach cannot be understood from a strictly literal reading of the text. The apostles themselves do not take a concrete, literal approach to interpreting the Old Testament. Imitating the thought processes of the Fathers, who are much closer culturally to the apostles, opens our eyes to more of the New Testament's message.
In the final analysis, it is difficult to fully comprehend the gospel message presented in the scriptures without realizing that the early Church, for which the New Testament was written, believed in baptismal regeneration, the real presence of Christ in the Eucharist (understood as sacrificial) and the Church as an organic structure put in place by the apostles.
If the authors of this series had fully appreciated this I think they might taken the plunge into the stream instead of dousing themselves with thimblefuls of water.
A final comment on the choice of the RSV. The major defect of this fine translation is the tendency to downplay the messianic implications of Old Testament texts, that is to "recover" some "original" text from the accretions of subsequent interpretations. Many of the texts that are interpreted messianicly in the New Testament are translated in such a way as to obscure rather than highlight this possiblity. A similar problem arises in the New Testament with the choice of "it" rather than "He" for the Holy Spirit. I'm not sure what alternative the editors had for this problem.