That's interesting, as I've seen that book on the shelf at the local Waldenbooks here every time that I've been in. I usually like to look at books that I've already got, to see if they've come out with a different cover yet.
It IS a great read, if not lengthy. In fact, it was well after the film INTERVIEW WITH TOM CRUISE ... I mean VAMPIRE ... came out.
One point of interest that she does mention is that our hero in the book is castrated at the age of 14, which was a bit late - historically speaking - for that to happen. Boys intended to be trained up as singers were usually cut at a much earlier age. Anne does mention in the notes that she took a bit of peotic license there, though.
However, it IS possible for a boy's voice to NOT have broken by that age. In fact, as we've discussed on the boards before, if you take a large group of boys, all 13 or 14 for instance and line them all up, it's amazing how different they all are. While the boy 3 houses down from me is almost 16 and STILL shows no signs of maturation at all, his cousin (my godson) is 14.5 and he's ... well, how to put it delicately? Puberty isn't being kind to him, let's say! His best friend, 13, looks more like an 8 year old as well. Puberty, and that period of life, is a strange one indeed.
Still, for anyone who's not read CtH, give it a read if you like that period in history and don't mind a bit of sex. It's well worth the time.