"Many Years from Now" is really good - but it's limited in that it doesn't cover anything really in dept past 1970. It's a collection of interviews with his good friend Barry Miles and it really is good in that it talks about 68-70 years well.
Paul McCartney interview by Vic Gambini is really good and it revolves around interviews in depth (sort of like the Playboy interview) in Dec 1973 and June 1975 and it covers a good bit of Beatle history.
Beatles Session by Mark Lewisohn - 1986? This is out of print but dates and sessions notes from every Beatle recording from 1962-1970. One of the best books ever on the Beatles without personal or gossioy crap.
I wouldn't recommend Blackbird cause it's a salacious in its stuff about Paul and Linda's life (Jimmy McCulloch drunk and trying to shoot Paul and Linda is a laughable exaggeration).
Bealtes Solo Years 1970-2001 is pretty good if you're into dates and things like that.
Pick up the 1989 Tour Book - It was Paul in his own words describing his life and his career. You can probably get it on E-Bay or from one of the collectors. I wasn't thrilled about it since i thought it was Paul trying to spin his life and his music in a way to counter-act against critics and do revisionism in terms of History (I was the Avant-Garde Beatle kind of pronouncements). But, it's at least Paul in his own words talking about himself in a refreshing albeit exaggerated form.
Mike mcCartney in 1981 published a book about Paul that has a lot of good early memories and pictures and stuff. It doesn't go deep but it was a book i enjoyed very much.
What can you say? I mean over the years - the Paul McCartney saga has been covered in a lot of detail. To me as the hard core fan, i still don't think there has been a book that has covered the man, his career, his music, his personal life, and his genius and faults - all done in a well, researched and detailed fashion. Paul is arguably the greatest popular composer in modern musical history and i think in the next 10-15 years we may see such a book happen. It would be nice to get cooperation from Paul, Lee Eastman, John Eastman, George MArtin, and his kids - but you know - George Martin is like 75 and using that as an example - there are a lot of people who know the history who will not live forever.
In my opinion, there hasn't been one book that has completed all the criteria for a great McCartney book. If i didn't have a family, i'd write it myself because i think (arrogant me) it would have to be one of the hard-core fans (like the dude who did the coffee table book Beatles sessions) who can deliver the goods. That dude poured (Mark LEwisohn) poured over every session of the EMI vaults - no easy tasks when listening to Within You and Without you for 56 takes or What's new Mary Jane. Now, that's a hard-core researcher