I'm not entirely convinced of the validity of women's history because going back through the ages and dredging up information about possibly not very significant figures and glorifying them on the basis that they are women seems a bit like distortion to me. How does women's history validate itself as a "proper" form of history and not just an extension of the women's movement?
In the last decades, as the history of women has become more integrated into teaching and writing at the academic level, it's "validity" is less and less in question. Admittedly, some of contemporary historical writing seems like women studies rather than history. Remember that the fields are now composed of "gender history" (history of male-female relationships), feminist history (feminism and feminist issues seen historically), and women's history (more encompassing and generally interested in exploring all aspects of women's past).