I recently read the graphic novel, and I though the overall story was great, but the treatment of Barbara was absolutely atrocious.
It's worth keeping in mind that these kinds of stories tend to be saying something, and by completely ignoring Barbara's perspective on what happened, a lot of people see that as the story saying that what she experienced didn't matter. That is not right, in a situation like this, I would say that her experience and reaction to what happened to her is more important than Batman's or her fathers. By looking at it purely from their perpsectives, they are (probably unintentionally) making it look like she is just an extension of those characters rather than a character in her own right. At least that's the way I've always understood the complaints about these kinds of stories.
It's a perfectly valid complaint, I just don't like people putting so much weight on their own opinions, getting all dramatic about it, & claiming that a rushed plot point actually injured them. It's not a new argument, we have a rating system thanks to it. We don't need to add a Ministry of Harmful Ideas into the mix.
It's also a kind of complaint that happens more often (but not exclusively) with corporate properties. DC often puts out comics that are for small kids & comics for Adults Only that star the same characters. This causes a lot of whining in certain circles. It would be like if Nintendo put out an M-rated Mario game. The number of whining fanboys & clueless parents would be through the roof, even if it was literally the best piece of art ever made.
Comics don't have brand consistency, and a lot of people resisted the change to a dark tone. A lot of people still whine about the 90s too, which I'm personally tired of listening to.