If you love your Arthurian Legends, you are going to love this book. The poetry is fully developed in its intricate combination of rhymes and alliterations. The complementary comments bring clarity to the original text and the different versions that never saw the light before.
I'm only sorry that Tolkien did not finish this, but what there is of the story is gripping. Especially fine are Guenever tricking the treacherous Mordred, Lancelot pondering indecisively whether to return to England, Gawain establishing a beachhead as Arthur returns from the continent to deal with Mordred's uprising. Tolkien had a gift for composing alliterative verse. Christopher Tolkien's introduction and commentary provide valuable background information.