I was hesitant to read something that expanded the Harry Potter universe, but wasn't written by JK Rowling. However, I did it anyway and discovered it actually adds a lot to the story in it's own right. Sure, it's story was created by her and it's canon (officially part of the universe as opposed to fan fiction which is only part of the author's conception of Rowling's universe.) Here are some reasons to jump back in with this play.
IT DEALS WITH THE BASIC PARENT-CHILD RELATIONSHIP
Most people on GAG have clear mommy and daddy issues. Seeing their beloved Harry Potter inflict psychological wounds on his own son not only continues the semi-realistic portrait of human experience that the original novels created, but takes them into a harsher realism than before. Albus is not the son Harry wanted and not the son we wanted Harry to have. Malfoy's child pays for the sins of his father and family and legacy of the death eaters. It fills in the gap that a story about an orphan left open--what does being someone's son or daughter mean in the context of growing up in this world?
GROWN UP RONALD WEASLEY
Ron has virtually no purpose in this play except to be comic relief and that's perfect. Even when he chimes in with useful bits its really just a repetition of conclusions already made by other characters so it feels like he's somewhat involved. Because the story moves so fast and has such little detail, Ron's well-timed humor helps us have fun during the more serious parts of the story. He's just a treat.
CYCLICAL TIME TRAVEL
I don't think it's much of a secret that Cursed Child deals a lot with time travel. Yes, it's sort of a cheap way of getting all of the characters, even the dead ones, involved in the story, but what it does is answer questions. Even more interesting, the fact that characters visit themselves means that, in effect, they were always there watching themselves the whole time even while we were reading Harry Potter and the Sorcerer's Stone for instance. I don't know about you, but it's cool to think about how time travel works in that context.
KEEPS THAT FAIRYTALE TONE
Harry Potter stories might deal with some serious stuff for children. It raises a lot of philosophical points and questions. Yet, the power to me is really in the story telling itself. It's whimsical and escapist. It makes you want to be at Hogwarts more than anything and this play achieves that same immersion even if the Queen didn't write it herself.
SHOWS THAT HARRY POTTER WILL ALWAYS BE INTERESTING
Even though Harry is WAY older now, he's still easily the most interesting most sympathetic character of the play. This is because he possesses a larger than life bravery that inspires us all. He'd do anything for anyone. Yes, there aren't many real life people that resemble Harry Potter's personality or spirit. Yes, Draco Malfoy, the conflicted pretty boy who probably should have ended up with Hermoine is much more relatable to people you meet in everyday life.
And yes, Albus Potter is a much more relatable hero because he's not just naturally good at everything he does like Harry was. But, Harry is still the one you want to read and watch do anything because he is just such a terrific character. I say this all to say that although JK says this is the last time she will allow the series to be touched--i think this play will prove to the world that Harry has a million more stories in him and even though he's no longer a child, he can still fascinate and excite us. He can still cast a spell.