Serviceable if this happens to be the first thing you ever read on historical biography, but otherwise, I think, it can be safely skipped. You might get something on the history of biography out of it, but not so much on its relationship to historical practice in the 2000s: in other words, on theory.
At least not much you can't find elsewhere articulated better.
Most negatively is the author's implicit assumption - judging from the examples - that all biographies are written on people from the modern era, where ego-documents are abundant, and the questions raised by what she calls "new biography" (or, probably, critical feminist biography) can easily be explored.