Personally, I'm not all that impressed with Pagels, sensing that, when it's a matter of orthodox Christianity versus one of the esoteric forms, she automatically has a predisposition for the latter and a bias against the former, and lets that predisposition color her scholarship.
Second, I've always considered Revelation (notice there's no plural) to be a coded message against Roman persecution, written to reassure the victims of said persecution that their oppressors would fall in the end and the reign of God would triumph, but done in such "hidden" language that any of the authorities who read it would just conclude that it was a bunch of nonsensical fantasies about "the end of the world." I think it's a mistake to look at every event and/or character in Revelation as pointing to a specific analogue in real-life.
Again, her contention that "the author was not a Christian" can be translated to "the author was not an orthodox Christian." However, I'm not too sure we can agree that the negative prophecies supposedly spoken by Christ criticizing the "seven churches" were really attacks on said orthodox Christianity. We simply don't know enough about the circumstances in those long-gone communities to know exactly what was being denounced there.
Finally, as to the "many books of Revelation," we once again get Pagel's particular hobby-horse about all the non-canonical writings she tends to champion. The fact is, there were lots of books of Christian "scripture" that didn't get in the canon. Not just "revelations," but gospels, epistles, etc. Over the first couple of centuries of the Church, many writings got used and then "winnowed out" for various reasons, so that, by the time of the first ecumenical councils, there was already a pretty general list of accepted books that wound up being codified as the "New Testament," and others that had fallen by the wayside. It wasn't, as some (hello, Dan Brown!) would like to assume, a case where the Bishops of the newly-legalized Church got together as a secret cabal and picked the writings that suited their particular biases to make as "official," while condemning and suppressing a bloc of equally-accepted writings as heretical; rather, there was almost a period of "natural selection" in the centuries beforehand that made the official canon merely a recognition of a given reality, not the creation of a new one out of whole cloth.
Personally, I don't put much value in the Revelation of John. Despite those over the years who have made an obsession of studying the book and applying its imagery to their particular times and circumstances, I don't find it to be one of the most valuable books of the Christian scriptures, compared to the gospels and some of the epistles. I think it's mainly useful as a "fantastical" epilogue to the Bible, a way of telling in the most striking form what Christians affirm: that, no matter how dark things may seem at any time, no matter how much it seems evil has taken control of the world, God will triumph in the end, and the eternal reign of peace and justice will come.