This biography of Richard Burton is, I would guess, highly unreliable as to details. Although Michael Munn, the author, was indeed in the entertainment business in minor capacities, I very much doubt he had the kind of access to Burton himself (or to his circle) that would allow him to quote, apparently verbatim, whole stretches of actual conversation so very focused and illuminating about Burton's life. My suspicion that in fact Munn was paraphrasing cribbed versions of secondary sources was confirmed when I compared his account of an incident involving John Gielgud with Sheridan Morley's Gielgud biography, and discovered word-for word-borrowings but written as if told to the author directly by Burton (the tip-off was the idiosyncratic phrase "idiot boards"). That said, Munn does seem to have had some access to Burton (though not perhaps in the chummy way he claims), as well as to some of the more notorious gossips in Hollywood like Roddy McDowall. He also actually gives us a bibliography of sorts, though only a "selected" one; so I suspect he did his reading.
This, then, was a quick read with a hefty dose of salt, reliable for at least the bare outlines of Burton's career, and likely also a pretty good reflection of the gossip about Burton over the years. It's not a very happy tale. Indeed, given whatever illness of the mind (or brain) he was suffering from, as well as his lifelong alcoholism, what strikes me about Burton is not the brevity of his working life but the fact that he managed to get as much good work done as he did.
I was relieved to read that despite his reputation of having slept with every leading lady he had, Julie Andrews (who shared the stage with him in "Camelot") was notoriously proof against his boozy charms.
There's got to be at least one better biography out there, and I remember hearing that Burton's own diaries have been published, so I may come back to him at some point. I'm really far more interested in Peter O'Toole (upon the subject of whom this particular book was pretty light, though apparently they were quite good friends), but reading this book has at least revived in me the desire to go back and watch "Becket" again.