There are real biographies and biographies written by fans. This falls in the second, which means it's not a good biography.
Here is the thing: biographies should focus on which kind of person the subject really is: Are they a good person or a bad person? Are they nice or are they assholes? And there is no exact answer for this, 'cause people can be nice sometimes and assholes sometimes. And you have to focus on those two; if you don't, you give a half-piece of who the person really is.
And here is the problem with the book: Because it was written by a Murray fan, everything he does is written in a way to give him a good light. He fights on the backstage? The other actors had an issue with him, not that he had a problem.
One such example is when the book discusses his divorces. On the second, it's not that Murray spent too much time away from home or wasn't lovingly; it was his wife asking divorce for "abandonment and physical assault". So the author didn't say Murray left his wife and, when together, used to beat her; she said he abandoned her and she said he beat her. By removing him, it turned a bad pair of actions into a passive description of Murray.
The same goes with everything "bad" that could be said about him (like the cited fights with other actors/actresses). And, in the end, it puts such quotes like "I never had a fight with someone that didn't deserve", just to clean up his slate.
Another example of fandom: There is only one movie in which Murray is a bad actor -- a movie with a completely disagree with the author of the book, "Scrooged". Everything else is cited as "a mess of a movie, but Murray gives a much needed appearance" as if Murray appearance was the only redeeming fact of every movie he appeared which bombed.
And this is just my tip for you, new reader: Read it with a gain of salt, as this is written by a fan who don't want to see Murray in a bad light.
Apart from all of this, it's a curious book 'cause, instead of going in chronological order, it goes in alphabetical order. Yeah, you read that right: Instead of going through the life events of Bill Murray, the book focus on things and people and movies in Bill's life: So every person who worked with him (maybe a few missing here), every movie made and declined, every sketch character, every family member, everything is there, in alphabetical order.
But even with this nonsensical ordering -- which is a good match for the portrait of Murray the book wants to give -- it is, still, in the very deep, a fan book which tries to make the subject seem much better than they actually are.