Mark Thompson of Moore College offers some helpful observations regarding the difference between patristic and modern treatments of the Trinity. Here's an excerpt:
Patristic trinitarian thinking and writing appears more overtly biblical, and specifically more exegetical, than much modern writing. Sometimes that exegetical work is tortuous and repetitive, as in some of Athanasius' orations against the Arians. Sometimes it is crisp and leaves important questions unanswered. Yet the Bible is in the foreground rather than in the background in many of the patristic treatments of the doctrine. In contrast, much of the modern discussion glances off the Bible and shies away from sustained exegetical comment.