I will not cover the entire book in this small review. More of what I took from it.
First, a small clarification. This book is by far, bar none, the hardest book I have read. But it's also one of the best-on par with Spenser's The Faerie Queene, if not slightly more complex. As I was unfamiliar with some of the more obsolete letters (thorns and yoghs and eths, in particular), I found some surprisingly helpful YouTube videos. I would recommend before you go in, that you at least read up on these, and Early ME's double (and sometimes triple) negatives in the speech (which confused me quite a few times!).
This book is a compilation of some more obtuse (and a few well-known ones (The Owl and The Nightingale)) poems. For those who don't know, J. A. W. Bennett was a member of the Inklings and filled the teaching position that became vacant after the passing of C. S. Lewis. His knowledge (along with that of his co-editor's) shine through in the introduction and the commentary, delving straight into the meanings of these poems (which, as should be no surprise to those who know the beliefs of the Inklings, are mostly religious). Some of these poems have some humour (The Owl and The Nightingale, the one where Lady turns into a dog (which has got to be a clever play on the early word 'bitch')), and some shockingly (and, in my opinion, wonderfully) violent ones, such as Lagamon and Havelok (the latter of which is a very brief retelling of the latter parts of the Arthurian Mythos).
In my opinion, though, the best poems are the ones closer to the end. They are very religious in their meanings (one is even called Kentish Sermon), but their verse is absolutely exquisite. My main favorite is the final one, Swales Warde: in it, several "fruits of the Spirit" (like Rightwiseness (Righteousness), Strength in Faith, others) are sitting having a talk with a fiend from hell (whose name in the poem I have already unfortunately forgotten). It comes across as a very Socratic dialogue, but in verse. And it's absolutely incredible. Compared to the Faerie Queene, I believe the poems in this compilation have even deeper meaning than Spenser literary masterpiece.
The spiritual practices of prayer and meditating on the works of Christ, esp. when you get further into the collection, is made to be very prominent, but it's never intrusive. I find it to be the exact opposite-it adds to the strength and power of these poems. As to the writing itself, it is wonderful, skillful. Five stars. Highly recommend if you don't mind spending 30 minutes on two pages