The Essential Trinity (P&R, North American Edition, 2017) is a collection of chapters by various contributors, edited by Brandon D. Crowe and Carl R. Trueman.
This book is definitely on the theologically academic side of the spectrum and that is appropriate given the nature of the subject matter. The trinity needs to be explored at a good depth – our God is unmatched in his depth and complexity.
“Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways!” (Romans 11:33 ESV)
This book is very solid and thoroughly researched, while not being too deep so as to make for tough sledding. It’s divided up into two parts – (1) New Testament Foundations – which essentially is a trinity-centric commentary of the NT books and (2) Practical Relevance – which, as titled, provides practical application of the doctrine of the trinity for personal and church contexts.
In Part 1, the various contributors diligently mine the Scriptures to shed light on their overall trinitarian structure. As a pastor preaching through the gospel of John at the moment, I perhaps most enjoyed the chapter from Bauckman – “The Trinity and the Gospel of John,” though he does get a bit bogged down in the eternal existence of the Son nuances. As Bauckman writes “The Gospel of John has played a hugely important role in the formation of classical Christian doctrine and in continued reflection on the Trinity” , and he solidly expounds that for us.
As one would expect, the letters of Paul are highlighted “alongside the Gospel of John as containing the richest vein of trinitarian theology in the New Testament.”  I appreciate the depth in which Brian Rosner wove together the trinitarian construct from various Pauline writings, with a particular focus on salvation. Highlighting the perfect harmony of our three in one God and each role in salvation he writes “salvation is the narrative of the saving Trinity’s acting on behalf of human beings.”  I found myself welling up in worship and gratitude (with a healthy bit of awe) as “nothing magnifies the grace like appreciating the triune God’s work in salvation. And nothing gives believers more confidence that they are known and loved by God than pointing out the collaborative activity of God, the Lord Jesus Christ, and God’s Spirit.”  AMEN!
The book has an appropriate balance of theological practicality in Part 1, touching on how the trinity impacts good works and conformity to Christ, and upholding the divinity of Christ and substitutionary atonement. As “some have argued (Gungor anyone?) that the Father’s sending of the Son to die amounts to an abusive, tyrannical act. However this misguided view severely misunderstands the trinitarian works of God.” 
Part 2 is really where the book powerfully shines in it’s application of the doctrine of the Trinity. “Not only does the doctrine of the Trinity identify God; it also illumines all of God’d works, enabling us to perceive more clearly the wonders of the Father’s purpose in creation , of Christ’s incarnation and of the Spirt’s indwelling.”  This impacts prayer, revelation, worship, and preaching and each are thoroughly addressed in their own chapters in Part 2.
What we believe about God affects our prayer life – “a healthy, vibrant prayer life depends to a large extent upon a good understanding of trinitarian doctrine.”  I was more than slightly convicted to remain diligent in promoting a robust understanding of the trinity from the pulpit, as was written – “not as an abstract truth, but as something with obvious, vital, practical significance.” 
Our three-in-one God speaks to us, through His word and as he reveals himself to us – as “the goal of revelation is not just knowledge about God, but the knowledge of God”  and the “centerpiece of God’s revelation is the gospel.”  We see the roles of the Trinity front and center as God the Father plans the redemption, God the Son fulfills the plan, and God the Spirit impresses the truths of the gospel on human hearts. [“Initiated by the Father, accomplished by the Son, and applied by the Holy Spirit – 270]
The basis of church worship must be an accurate knowledge of who God is and what he has done, according to His Word. Letham reviews key passages relating the doctrine of the Trinity and worship. [Eph 2:18; John 4:23-24] “Since Christian worship is determined, initiated and shaped by, and directed to, the holy Trinity, we worship the three with one undivided act of adoration.”  There was an air of opposition to an “anti-liturgical movement” in this chapter, which came off as having an axe to grind, but the points of intentionality in Trinitarian worship were well taken. However, getting real practical, a properly informed Trinitarian worship perspective should affect the way we treat people – specifically, it should unite, not divide.
Finally, the chapter on the Trinity and Preaching was the one that I found the most helpful. It encouraged me in the importance of proclaiming God’s word where our three-in-one God actually speaks to us. “Without God’s word we simply would not know God.”  There seems to be a frustrating increase in preachers and authors claiming direct revelation from God, and this chapter clearly reinforces the power and uniqueness of God speaking through His Word. “The fact that God is triune, and always speaks in a trinitarian way, should inform both the content and the intent of Christian preaching.”  As Reeves writes, “preaching should foster sincere worship”  and this book as a whole strikes a good balance between the academic and the inspirational.