My main quibble of this story is that Moore seems to get tired of Promethea after her newest incarnation appears and switch the focus to hermeticism and magickal philosophy. The development of the character gets lost in a horde of Goetic demons and otherworldly realms.
One thing that puzzles me is the idea that somehow Promethea is a more authentically female superhero than those who have gone before, instead of being a "man in a woman's body" like Roger of the 5 Swell Guys. How is Promethea/Sophie (created by two men) more a real woman than Wonder Woman (created by William Moulton and Charles Gaines) or Buffy the Vampire Slayer (created by Joss Whedon)? At least the Bride of "Kill Bill" was created by a man and a woman.
However, Moore on a bad day is still levels above plenty of other writers, so this is worth checking out.