There's an
interesting discussion at the moment over on
discworld about an academic paper examining Terry Pratchett's portrayal of female characters, specifically looking at Granny Weatherwax, Nanny Ogg, Magrat, Agnes Nitt and Tiffany Aching. The author of the paper makes some interesting points, but seems to be overlooking how Pratchett operates in subverting the tropes in genre fiction. That said, and as much as I love Terry Pratchett, some of his female protagonists niggle for a reason I could never quite put my finger on; I found that Susan never clicked for me the way that his other characters do, and I disliked Monstrous Regiment but couldn't identify exactly what bothered me about it. Polly and Susan do seem to be cut from a similar mold...
For all that, though, Pratchett's female characters are still miles ahead of most genre fiction, and he's brilliant with taking the limited roles from traditional fantasy archetypes and reinventing them.