I usually oppose interpreting the Bible “metaphorically” because the authors of the original texts probably understood a lot of this stuff literally.
But for hell, it’s hard to say. I think much of the imagery in Revelation is meant to be literal. For example, stars will fall out of the sky. This sounds stupid to us because we know that stars are huge balls of plasma thousands of times bigger than the Earth, but the ancient Jews and Romans thought that stars were tiny points of light or lamps in the sky, and they thought meteors were simply falling stars.
A lot of the imagery in Revelation seems very weird, and it is. Some of it is code, especially the imagery involving numbers. When you see the number 12 it’s supposed to represent Israel. Seven represents power; four represents wholeness or totality. Some names, like “Babylon,” are obviously meant to be symbolic of modern events (Babylon is Rome). But then, just because this stuff is symbolic doesn’t necessarily mean that the early Christians didn’t think it was literally true.
Revelation is actually part of a long and colorful tradition of apocalyptic texts; some Jewish apocalypses date to the much earlier Babylonian captivity, but the genre was also popular in Rome. (Apocalypses typically involve (1) a journey to heaven, where a vision is “revealed,” and (2) a description of violent “comeuppance” of the occupying power where God wreaks havoc on unbelievers). And some scholars think that this genre should be understood almost like action or horror movies. It’s supposed to be spectacular and over the top. And, like action/horror movies, new apocalyptic texts often seem to try to “outdo” older ones with gory and spectacular imagery.
So if you accept this view (and I think it’s reasonable) then asking if imagery from Revelation is supposed to be “literal” is a bit like asking if a spectacular action scene in Avatar or Transformers is supposed to have “really” happened. The answer is, in the world portrayed by the movie, “yes.” The problem is that this world is fictional.