As I've said before, I like Mary as a character. It's good to see a strong female character who is both intelligent and warm - although I must admit that I also liked Irene, who was brilliant but cold. Anyway, Mary is very likeable but I do think she makes the relationship between the two men less focused. It's always been Holmes and Watson, the classic double act, from the beginning. I think Conan Doyle recognised that core relationship and quietly wrote Mary out of the stories. I don't think this will be the fate of the current Mary. After all, the writers could not even bear to kill Irene, and sent in Sherlock to save her at the eleventh hour. I think it will be okay if they keep her as a fairly minor character like Molly or Lestrade, but I think that they will lose focus if it becomes the story of Sherlock, John and Mary (and Baby Watson), rather than the story of Sherlock and John. Of course, I could be wrong and probably am.
I am hoping that the next episode will be quite dark and dramatic, to shut up all those who keep whining about this series being different to Series 1& 2. Most of the tv critics seem to have enjoyed this series and we, the fans, have mainly been delighted, but there are a lot of people moaning that it has been too self-indulgent and/or too much influenced by the fandom. I suspect that most of those complaining are people who wanted the crimes foregrounded, rather than the characters. As far as I'm concerned, the interest lies in the people, particularly Sherlock, rather than in whatever dastardly crime is being foiled, but that isn't everyone's view. As fans, we love to ponder "what if" - what if Sherlock had to make a best man's speech? What if John and Sherlock got drunk? - and all fanfic is an attempt to answer those questions. Some viewers, however, just want cops and robbers. I hope that episode 3 blows their socks off! And I hope the BBC has the good sense to ignore the doubters and press on with the next series (and a bit quicker this time, please!)