Frank Sinatra was always a puzzle -- he sang like an angel, behaved like a jerk, and yet was apparently an extremely generous individual who kept his many charities secret.
Donald Clarke sits with all the contradictions of Sinatra, both musical and personal, without attempting to simplify them. The reviewer below who complained that the book is like an extended essay is right. Clarke does not attempt, in this relatively slim volume, to write the definitive biographical work. It is instead a shrewd, opinionated, and often funny review of the man and his music.
I'm not a FS fanatic, but I do own about 40 or 50 of his albums, which I guess makes me more than a casual fan. I almost always agreed with Clarke's musical judgements (although I think rather more of "Live at the Sands" than he does) and found a lot of value in the way he attempts to separate Sinatra's own bloviations from the facts (e.g. was Mitch Miller really responsible for how bad much of Sinatra's mid-50s work is? Not really, says Clarke, and gives reasons for this opinion).
This book is not a replacement for a full-length biography -- if you want the details on who slapped who first in every fight he had with Ava Gardner, you'll have to go elsewhere. It's also not a replacement for an annotated discography, although it made me hungry for one -- I thought I had a pretty good handle on Sinatra's recorded output, and Clarke made me realize there's a lot I don't know.
As for Clarke's writing style, I say "bravo." Judging by the impish grin he's wearing in the jacket photo, I'd say he's well aware of how provocative some of his comments are, but there's nothing arrogant about this book. Clarke has his opinions, and states them very strongly, but it's clear the reader is welcome to his or her own. If you're the sort of reader who is secure enough to enjoy strongly held and amusingly stated beliefs rather than be upset by them, I recommend this book most highly.