Here's a hazardous question that can often be asked and answered glibly; what does the female fan want? According to this interview Steven Moffat, co-creator and best writer for the Sherlock Holmes pastiche television series Sherlock, women want Sherlock Holmes.
. . . it's got such a huge female following. The original stories had a huge female following, which I'd never forgotten, and that's because the Victorian ladies liked the way Sherlock looked. (Laughs.) So I thought, use this massively exciting, rather handsome man who could see right through your heart and have no interest . . . of course, he's going to be a sex god! I think we pitched that character right. I think our female fanbase all believe that they'll be the one to melt that glacier. They're all wrong, nothing will melt that glacier.
I wonder if this influenced his decision to set the second episode of the new season around the marriage of John Watson and Mary Morstan. Morstan appears in the Holmes novel The Sign of Four. The book depicts Watson's proposal to her but, although he marries her and The Sign of Four is only the second Holmes story and therefore followed by the bulk of the series, Mary essentially never appears again though Watson does refer to his wife now and then and is married. Mary eventually dies and her death isn't even directly mentioned, only vaguely alluded to when Holmes expresses condolences to Watson in The Empty House. The marriage is so inconspicuous in the stories that adaptations frequently omit the existence of Watson's wife entirely.
In Sherlock, Mary isn't only a full fledged character we see her outwit both John and Sherlock to get them to go play outside together (go on a case) to reaffirm their friendship despite John's upcoming marriage.
Holmes' reluctance to engage in society for the sake of normal human companionship in the stories was portrayed as something of a dysfunction in the Jeremy Brett series but in the new show it's shown as something that renders Sherlock, as he himself observes with smiling self-deprecation, a "baby". In the stories and the Brett series, Holmes and Watson could have fun together. They would go to the symphony together. Although Sherlock in the new show plays the violin, the two men never seem to share a laugh. Even their night of drunken revelry shows the two being oddly solemn--Sherlock using beakers for beer in order to make some sort of precise calculation regarding alcohol and body weight while John is the quietly incredulous foil. Both seem a little too high strung for their own good. This sort of thing seems to have been created to give the female characters, like the bridesmaid introduced in the episode, Mrs. Hudson, Molly the coroner, and Mary something to feel maternal and vaguely pitying towards Sherlock about.
But, as Moffat observed, women were already fans of Sherlock Holmes. Do we really need this false equivalency? Well, the episode is fun and really cute. The murder mystery makes no sense--it relies on people not noticing being fatally stabbed and a survivor of such a stabbing being unable to provide any information about it afterwards. But it was a cute and fluffy show. That may not be what one goes to Sherlock Holmes looking for, but if one takes it out of context it's a bit of harmless fun.
Still, my favourite episode of the series so far has been "A Scandal in Belgravia". Rather than dumbing Holmes and Watson down for the supposed benefit of female characters meant to be average, "A Scandal in Belgravia" has an extraordinary woman for Sherlock to match wits with. Of course, Irene Adler can't be around all the time--she only appeared in one of the original stories. But the fact that she's as clever as Holmes isn't the reason for her only appearing once, I would say. I think it has more to do with the fact that the stories were about Sherlock Holmes.
Perhaps someone ought to make another series about a brilliant female detective. Oh, I am looking forward to the Veronica Mars movie.