and has some of the BTS stuff (not a whole lot) that is much more nuanced and discussed some of Whedon's horribleness.
He also bullied Nicholas Brendon and James Marsters, and they are both still dealing with the abuse on set. (I don't remember exactly what the book says because I've read so much...Katz tends to fanboy over Sarah Michelle Gellar instead of Whedon if I remember correctly). It was also more Buffy (the show) focused if I remember correctly. But I liked it better and you might enjoy it.
But a lot of it is what us fans already know :)