There is a lot of good here, but not enough nuance.It is good to draw out and emphasize the overarching, timeless message and theological principles from Revelation, and not to get lost in the details and miss the forest for the trees. But this can be done whether one interprets the details as being past or future.
It is also good to beware of idolizing one's nation, thinking it is the kingdom of God on earth. But his critique of American civil religion, I felt, was simplistic. One the one hand, completely de-sacralizing government is a thoroughly modern idea, and Gorman fails to recognize the ways in which modern, secularized views of government lend themselves to divinizing and worshiping the state. The Bible in fact instructs us to see and treat government, in all its forms, as sacred, because it is from God. This view of sacred government in fact resists idolizing the state, since God remains in the picture, and because a distinction is maintained between God and human government. The authority and honor government possesses is derived from God as a stewardship, is not at all ultimate, and comes with responsibilities and limitations.
Gorman's pacifism is built upon an interpretation of Revelation 5 and 19 that does not follow, finding more there than is allowed. The subject of violence is too large to tackle here. But Gorman's view, I think, is naïve and is certainly not demanded by the texts he appeals to. One of the weaknesses of this book is that Gorman hardly lets Revelation interact with other books in the canon, even though he does call for just that at the end of his monograph. But a responsible reading of Revelation would surely demand this.