MIXED MEDIA : ** 1/2 “MADONNA: UNAUTHORIZED” By Christopher Andersen, <i> Simon & Schuster </i> (<i> $20)</i>

Madonna already enjoys at least the pretense of living her life as an open book--see “Truth or Dare,” in which she presents herself as Marilyn only with brains, business sense and bad language--and Andersen (a veteran Time and People journalist) reckons to open it a good bit wider still. He succeeds, for anyone who hasn’t already OD’d on this year’s nonstop media Madonna-thon. There are some juicy new morsels of detail but no thematic surprises in this well-researched, unflattering account: She’s portrayed as ruthlessly ambitious, sexually voracious, brilliantly conniving, easily offended, given to convenient betrayals and, by the end, someone most readers will be just as happy never to have known. As a portrait of raw striving and street smarts, the pre-stardom stretches are fascinating; later, in the Sean and Warren years, it gets into Enquirer-type stuff that, despite the purposely unlurid writing, leaves you feeling dirtier for having devoured it.

Items in this periodic survey of pop-related books, videos and laser discs are rated on a scale of one star (poor) to four (excellent).