I don't really give a shit. It doesn't seem to violate the rules of time lords, so what's the issue? We have female starship captains too, no biggie. Let us not forget the bravery of Captain Kate Red Mulgrew. She was the second most badass, after Sisko.
The whole "as a feminist" announcement by the actress makes me cringe a bit. I still don't give a shit. Do your job, do it well, don't pander to ideological sensibilities and I think the Doctor Who Universe will survive just fine. None of this 'wink wink, move over boys' shit. Make her seem above that, not mired in it, otherwise you reduce the character to a token prop, and that seems contrary to the nature of Dr Who, who is awesome in spite of the form he or she takes, not because of the form he or she takes--that last point was sort of my issue with Ghostbusters, that I never really cared they were women, but it became all about the fact they were women, that was the big gimmick and selling point and it actually diminished them, IMHO; Rey in Star Wars on the other hand, or Furiosa in Mad Max are cool as hell, no one made a big deal about their genders, they were badasses because they were competent, not because of their genitals.