A female Doctor will really irritate and annoy people who deserve to be really irritated and annoyed, so I am in favour of it.
I don't think I deserve to be really irritated or annoyed. While I won't stop watching the show if they make the Doctor a woman sometime in the future, I really wish they wouldn't. I think "Grandfather" should always remain, well, male.
I don't have a problem with the Doctor being of any ethnicity. That's all just pigment, after all. Just leave the gender bending to the Trills.
Not that this is a deal breaker or anything.