The version of the book I read was from 2001 and included a new introduction that made it clear that A) this had been Bull's first book, B) she was in a rock band, and C) the book had remained quite popular in the intervening 14 years.
War for the Oaks is urban fantasy set in Minneapolis in the 1980s (when it was published). The main character is Eddi McCandry, who plays guitar and sings in a rock band. The book starts with the disintegration of her current band - co-incident with her break-up with another musician in the band. She's forcibly recruited by a Pooka (Bull spells it "Phouka," but mentions the invisible 6' rabbit in the movie "Harvey") to join a war between the two courts Faerie.
Bull being in a band herself has both advantages (she knows what she's talking about when it comes to music, or playing bad crowds) and disadvantages (the whole thing reeks of wish fulfillment). And then there's the problem of the "secrets," things she thought she'd reveal to her readers slowly - notably the origins of two of the new band members. I figured that out within a page or two of their arrival. And the final love interest, also meant to be a secret/surprise, which was obvious by about the 50 page mark. The writing was definitely unpolished, but in the end I did enjoy the book.