I'm currently ploughing my way through John Campbell's biography of Margaret Thatcher, because it's on my reading list rather than a great personal desire. Nothing against the iron lady but I find biographies generally very tedious, particularly the early lives of them (where often they're not very different from the young lives of many other people who didn't go on to become very important). Plus the writers usually know that this is a dull part and get tempted to start finding clues to later decisions in the smallest details of childhood.
So far what's far more interesting is where it notes how Thatcher herself (and others) have attempted to portray her childhood rather than her lifestory itself. Or in short, the most interesting parts of this biography are the bits that didn't happen.