I saw this thread last week whilst browsing but didn't have time to reply.
I read it when it first was published and would give it a slightly mixed review. Many interesting stories, important comments about piano playing and music, but sometimes a bit nasty, outrageous, and too gossipy for my taste.
I know what you mean, though I think it's not outright nasty. I like the book a lot, but I don't think it would necessarily be to everyone's taste.
I wrote a brief review of it last year, so I'll quote that:
"Firstly, two warnings! The book is not cheap (you do get over 800 pages!), and it's probably not for those of a prudish disposition either. There is a vast amount of scurrilous gossip within, written in an often waspish, though not malicious, tone. Horowitz getting caught stealing vegetables from his neighbour's garden, Virgil Thomson being arrested in a raid on a gay brothel, Lazar Berman rudely stuffing his face at a buffet, a flatulent conductor: it's all there, and much, much more! Personally, I think it's an absolute hoot, but some might find it a bit much. There is also name-dropping on a truly epic level.
The book is written in a conversational vein, liberally peppered with exclamation marks. I've seen some reviews where people have said it is crying out for a decent editor: personally I didn't mind the informal style, but it did nag me that he doesn't appear to know what a limerick is (not that his poetry is any better than doggerel).
He offers forthright opinions on a vast array of musicians, especially pianists and conductors. (In passing, there is a short chapter devoted to having a really serious go at Isaac Stern). I was amused to read his comments on "Al" "Brendull" and "ugh-text" (Urtext) but he is preaching to the converted in this department. Jorge Bolet, on the other hand, had a very fine military uniform, of which he was deeply jealous! Lang Lang is described as "the J-Lo of the piano".
Probably the best chapter is that on piano technique, phrasing and sound production (characteristically entitled "Banging is for the bedroom"!). I'll be reading that long after the tittle-tattle has outlived its amusement value.
In summary, 4/5: a great read which sometimes becomes too much. An inimitable account of one of the piano's individualists. Recommended to lovers of romantic pianism, with a few reservations."