I’m gonna be really controversial here and say that my reaction is…meh!
They’ve been dropping some serious hints back from Matt Smith’s time as the Doctor through to the Master regenerating as female and a Timelord changing from male to female in front of our eyes plus Capaldi was always advocating a female replacement.
Frankly I’d have been more surprised if they didn’t do it.
I know the internet has been alight, people are saying it’s just to be PC. My hope is that they’ve done it to be interesting, which is something the series could do with. My reaction is meh because I just don’t feel as invested in the series as I used to be. It’s still fun to watch but not the Saturday night must-watch it has been – half of the current series is still backed up on my DVR so maybe they could do with a radical change.
We shall see