Anyone who writes a biography of Paul McCartney has a problem, which is, somewhat surprisingly, that McCartney can be a pretty boring subject.

Well, yes, he is an ex-Beatle. And he has had more than two score gold records and he's worth at least a half-billion dollars.But McCartney leads a determinedly unobtrusive, middle-class life with his wife, Linda, and persists in recording albums that in no way indicate he was part of perhaps a remarkably creative and influential pop group.

Quite frankly - and sadly - he's become boring, and this book reads that way.

There is good stuff in "Yesterday," chiefly colorful descriptions of the Beatles' loss-of-innocence period in Hamburg, West Germany, and some documentation of the group's financial situation, which continues to be a mess.

But the book could have used better writing and more insight - just like most of McCartney's later songs.