Wilfrid Harrington, O.P. has written a scholarly analysis of the Book of Revelation, but his theology is heretical, and decidedly not Catholic.
For instance, Fr. Harrington denies the existence of Satan, stating, "Satan is a powerful symbol, representing the whole gamut of evil and its infectious presence in the human race".
What is more troubling, he seems to glowingly accept the teachings of his fellow Dominican, dissident theologian Edward Schillebeeckx. In an Excursus at the end of this book, Fr. Harrington states there will be Universal Salvation ("Universal salvation means that all human beings will finally be redeemed by God's gracious love"), and "There is no negative eschaton" (meaning there is no eternal hell). He agrees with Schillebeeckx's statement, "But there is no shadow kingdom of hell next to the eternally happy kingdom of God." Were there any confusion about his stance, Fr. Harrington states, "Humans, not God, have invented hell."
What these two theologians are telling us is that there will be no eternal hell, in direct opposition to the Gospels, and in direct opposition to the teachings of the Catholic Church.
While it would be pleasant to think that no matter what we do in this life, there will be no possibility of eternal damnation, this is not what Jesus Christ himself tells us in the Gospels.
I heartily agree that the Book of Revelation is indeed a message of God's love and mercy for us; it is also a Book about God's justice. We mock the Gospels if we deny the existence of Satan, and we deny God's just nature if we deny the existence of an eternal hell.
So, while his scholarship is decent, his dissident theology casts a pall (in the truest sense of the word) over this book.
To any Catholic, I would say "Let the reader beware".