Great that they're breaking the cycle of apparently ever-younger doctors: there's no doubting that Matt Smith worked for many viewers, but the frenetic puppy act seemed to affect the pace of the shows, making them feel rather light-weight even when the plots were fundamentally serious.
Peter Capaldi should provide a great antidote, in some ways taking us back to David Tennant territory - another Scot who can play authority and gravitas, yet has a good track record in comedy whilst also being able to suggest an eccentric and even sinister edge - giving the opportunity for the series to achieve a greater depth than it has shown recently, and perhaps even recalling the character of the Doctors of earlier days.
As for a female Doctor, while it's no doubt a future likelihood, it would surely make the present story arc of the relationship with River Song very confusing for younger viewers, and create something of an audience backlash with parents having desperately to find some way of answering some potentially awkward questions....
Perhaps a regeneration into the 14th Doctor with a gender change could be a solution to the finite number of regenerations the Time Lord is permitted, since it could be classified as a mutation rather than a regeneration: the result would no longer be a Time Lord, but a Time Lady!
