Harry Potter and the Cursed Child is a bit of an unusual entry into the Harry Potter canon. Not being a novel makes it a completely different reading experience than the core 7 books that we love, being written by multiple people (rather than just J.K. Rowling) makes some of the characters have a slightly different feel, and centering the story on a character other than Harry makes it inherently feel different.
I for one loved reading it and I look forward to the day I can eventually see the play itself to experience it the way it was designed to be experienced, but not everyone agrees with me. People speak out against the differences in Time Travel between this story and Harry Potter and the Prisoner of Azkaban. People speak out against the differences in the way Ron Weasley is characterized. I tend to disagree with them, I think Ron seems perfectly normal and the Time Travel is consistent with the warning Hermione gives to Harry in Prisoner of Askaban.
One thing that has been hitting the media lately is a statement by a few people that “Harry Potter and the Cursed Child lets down women and betrays Hermione’s legacy” (Mashable) or “How Hermione Granger Is Portrayed in Harry Potter & The Cursed Child is Offensive To The Fans & The Character.” (Bustle).
As with the other claims, I disagree with this assessment and wrote an Essay for the Harry Potter Lexicon to dispute it. Please give it a read and see if you agree with me or not.