Instead, she's a woman! And she's Irene Adler!
I truthfully did not see that one coming. I am pleased with it, as it shows us the writers aren't afraid to take risks and play with the Sherlock Holmes canon beyond making Watson a woman.
On the other hand, I don't know how much more we will get. I suppose it depends on how often they can get Natalie Dormer to guest star.
A friend and I have a disagreement over the BBC's version of Irene Adler. She loved the character, while I was displeased with the fact that she didn't ultimately beat Sherlock like in the canon - she never seemed like a true equal in the end. The BBC Moriarty however, could be even smarter than Sherlock.
Here, Sherlock once again triumphed over both, but I feel that this mash-up of Adler/Moriarty is more on his level. She concealed the fact they were the same person for years from the best detective mind in the world, and was able to nearly destroy him by driving him to abuse drugs.
Their love/hate relationship is very intriguing, I hope we get some of it every season.
P.S. The sex will be mind-blowing when it finally happens again.