The idea of Stephanie Brown as Robin was so fresh and strange as a direction, but was handled so clumsily and with such obvious institutionalised sexism that it was pretty vile to witness, both as a cultural observer and as a fan who's also a feminist.
Essentially, for those not familiar with the character or with Robin's larger back story: when the second Robin, a boy named Jason, died, Batman created a memorial out of his costume in the Batcave. Stephanie was the fourth Robin, and her costume was different to the three boys who'd had it before her in that she sewed a red skirt for herself. Just a few months after her first issue as Robin was released, Stephanie was tortured to death with a power drill by a villain, and then died with Batman at her bedside.
The sexualised violence alone was pretty vomitous, but what made it so, so much worse for me was that Batman promptly forgot her. DC's Editor in Chief had the gall to respond to questions of how her death would affect future stories by saying that her loss would continue to impact the stories of the heroes -- how sick is that? Not only is the statement clearly untrue, since the comics were chugging along their merry way with no mention of her or her death, but it was also an example of the ingrained sexism of so much of our culture. Stephanie herself was a hero, and had been a hero for more than a decade's worth of comics, but the Editor's statement made it clear that he only thought of male characters as heroes, and the females as catalysts for those stories. It was a very clear example of the Women in Refrigerators trope, which has been a problem with superhero comics for far, far too long.
Lots of good stuff here on Spock on Uhura, and on Carrie Kelly in Frank Miller's The Dark Knight Returns:
Robin crosses all sorts of imposed gender boundaries, both literal and figurative. Carrie Kelley, for example, the young girl who becomes Robin in Frank Miller's The Dark Knight Returns, is referred to by a news broadcaster as 'the Boy Wonder'; she looks completely androgynous in-costume, and so is assumed to be a boy. Dick Grayson and Tim Drake both assume female identities to go undercover in numerous stories -- Dick even played Bruce's wife on one occasion back in the forties -- and Stephanie Brown's superhero identity before she became a Robin, the Spoiler, is thought to be a boy even by her own father.
Never understood why Miller made Kelley take on a different identity in The Dark Knight Strikes Again.