Barry Miles & the Ginz bio
Don't look to Barry Miles (who has also written a bio of Kerouac and Burroughs) for much depth, much critical analysis, or much scholarly explication. His biographies are generally surface-level records of facts and don't go into a lot of detail. The Ginsberg bio is no different. It is, however, a good read and does a good job of presenting an overview of Ginsberg's life, at least up until the early 1980s. Not much about his life beyond that.
A somewhat better bio of Ginsberg is Michael Schumacher's "Dharma Lion A Biography of Allen Ginsberg"