Irene Adler isn’t the only woman Holmes respected, and indeed, what kind of point would it be if she were? Then it just says that Holmes met one woman who was worthy of respect; the end. But turn it another way; look at it under this light: Holmes met a woman who made him realize that there was more to women.
Before this (chronologically), he had been sympathetic to women, always ready, with Watson, to take on the role of knight-errant. Mary Morstan even refers to them as such in The Sign of Four. Holmes says of Miss Morstan, now Watson’s fiancée, “I think she is one of the most charming young ladies I ever met, and might have been most useful in such work as we have been doing. She had a decided genius that way; witness the way in which she preserved that Agra plan from all the other papers of her father.”
There is little evidence in the stories of an active “dislike” of women; although Watson might have been fooled, the reader seldom is. As for a distrust, Holmes didn’t trust anyone, and I would go so far as to say there are examples that show he didn’t trust Watson completely, nor was he worthy of being so trusted himself, which he probably knew. He knew the proscribed conditions of women’s lives, and, because of this, he was not unsympathetic to them.
If meeting Irene Adler opened Holmes' eyes a little further to the fact that women could reach beyond their assigned roles, that’s a much more exciting concept than her point being that she was the one woman who equaled or approached equaling or beat him.
(In fact, there is debate about whether she was the woman mentioned in “The Five Orange Pips,” when Holmes says, “I have been beaten four times—three times by men, and once by a woman.” The case is dated earlier than “A Scandal in Bohemia,” so we are left with the possibilities of misdating or a woman who beat Holmes before Irene Adler, perhaps not such an honorable woman or one so worthy of respect.)
But say that Adler’s narrative function is to make Holmes more aware of the possibilities of women. Mary Morstan had a decided genius for detective work, but she married Watson and was happy with that kind of life. Perhaps it was so for all women.
Then there is Adler, enjoying playing the game against him, someone with whom he is ultimately more sympathetic than his client. And in the end, she shows the king mercy when she has him in her power; this is what puts her on a “different” (higher) “level” from the king. Holmes is not in love with Adler, but he sees her more clearly in the end, understands and admires her. His education in the matter of brave, intelligent women is underway.
In “The Copper Beeches” (a case usually dated by chronologists as 1890, two years after the date given for “A Scandal in Bohemia”), Violet Hunter functions very much as the investigator on the scene (in his fascinating book, The Secret Marriage of Sherlock Holmes, and Other Eccentric Readings, Michael Atkinson writes that “Violet is as bright and observant as Holmes—and is the better detective”) and wins praise from the consulting detective: “You seem to me to have acted all through this matter like a brave and sensible girl, Miss Hunter. Do you think that you could perform one more feat? I should not ask it of you if I did not think you a quite exceptional woman.”
As late as “The Lion’s Mane,” when Holmes has retired to keep bees in Sussex, he says of Maud Bellamy that “she possessed strong character as well as great beauty” and would “always remain in [his] memory as a most complete and remarkable woman.”
The only woman Sherlock Holmes ever respected? Not by a long shot. An important part of the evolution of his character? Hell, yes.