The publication of this book is a welcome addition to what is becoming a renewed focus in Western Christianity; namely, focus upon theology proper, God in God's self. With all of the anti-this & that and solas of the Reformation, God the Father, and thus a proper understanding of both His Son and Spirit, had been distorted and neglected. For a variety of reasons, not the least of which is renewed contact with the Eastern Orthodox liturgical/theological tradition, Western theology, both Roman Catholic and Protestant, is recovering from its amnesia. While this slim volume is not one that I would put on a top ten list of books to read when thinking about Trinitarian theology, it does have its merits.
Alister McGrath's essay on Evangelicals and Trinitarian theology isn't too engaging (is he ever?), but does rightly call us to have a mental humility before the mystery of God. Without limiting God to transcendence, he rightfully remarks that we must stick to our data, and not get so absorbed in our thoughts about God that we forget that loving God covers over a multitude of "unknowings", and that this is just fine. This is akin to the Orthodox approach to apophatic, or negative, theology. God is fundamentally a mystery in which we participate, not understand. This is a good way to set the tone for reading the other essays.
Massey's essay on African-American spirituals notes the role of the Holy Spirit. While useful, I found it to be rather narrow for a larger reading; likewise can be said for Packer's reflections on the Puritan John Owen. In at least two other conferences I have heard him present on Owen and at this point it just doesn't do it for me. Too narrow for general readership.
Essays that I found more general and insightful would include Matthew-Green's reflections on the Eastern Orthodox approach/experience of God as Father, Son and Spirit in Her art & architecture. She reminds us that it is in the context of worship that we come closet to "knowing" God in a communion of love, as the Church is the Body of Christ. That can never be said enough, and one might find in this approach a useful metric to just how Christian much of what passes for worship actually is (or isn't). Dulles' essay echoes the liturgical aspect of theology, with his reflections upon the nature of baptism.
Charry's critique of Barth, Jenson and LaCugna is through her Augustinian lens. This means that she wants to temper the "social" aspect of the Trinity with Augustine's notion of divine simplicity. I am not exactly sold on this at all, but it will resonate with classical Western theology. It can be a tricky conception, but it does serve to guard against tritheism.
Most useful for myself has been George's critique of Muslim critiques of Christian trinitarianism, showing that Mohammed fundamentally misunderstood Christian theology on this point by believing that Mary was the third member of the Trinity and that she had sexual intercourse with God to spawn Jesus. While Mohammed may have been exposed to a heretical Marian cult, and developed his ideas of Christianity form that, it dose show that the Quran is off-base in its critique of the Faith. Robert Louis Wilken's Remembering the Christian Pasthas an excellent chapter on this topic as well.
There are a few other essays that are included that yo can see in the index above.