Best Of

SPOILER ALERT OBVIOUSLY.
I don't think I could state everything eloquently right now. Here's a general list that perhaps could be better explained expanded upon later:
-The story is kind of unoriginal. It takes pieces of the seven books and rehashes them via time travel. Boring.
-The typical statement that it reads like fan-fiction speaks true to me. It seems like Jack Thorne took a lot of trendy headcanons from the internet and created a play based on them (Voldemort + Bellatrix, Albus being in Slytherin, Rose and Scorpius, etc.). They did minimal research about the world that Rowling established and contradicted many original plotlines and devices.
-The dialogue and overall feel did not resemble the feeling that was established by Rowling. That's what happens when someone else writes, I guess. Every author has his or her own style.
-The characters changed personalities way too much for me. Ignorant Hermione? Bitter Hermione? Arrogant and Uncaring Harry? Dumb, Side-kick Ron?
-Voldemort and Bellatrix apparently getting together to produce an heir. I think it is flat-out stupid. It goes against everything we know about Voldemort's personality. Rowling said he was aromantic, I thought. Why would he want to produce an heir during Harry's sixth year anyway (Bellatrix pregnant in Deathly Hallows?)? He didn't know anyone knew about his horcruxes. He thought he was going to live forever. WHY? I personally like to believe that Voldemort was sterile after splitting his soul into eight pieces, drinking unicorn's blood, and losing and regaining a body. I mean, his eyes turned red, his nose was reduced to slits, what else changed, ya know?
-Where did the prophecy come from?
-Why do they call Voldemort by name in the alternate timeline?
-Cedric Diggory a Neville-murdering, death eater?!
-The way Harry spoke to Albus Severus. Never. I don't care what people say. Also, his kid is a brat.
-Don't they whip up a batch of Polyjuice Potion in one day? Doesn't that take a month?
-The whole time turner thing does not make sense. AT ALL. Interestingly, the month after the script for CC was released, Rowling posted on Pottermore that anyone who attempted to time travel more than five hours would die. I find it intriguing she wrote that. Also, how did Draco have a time turner?
-Speaking of, Rowling established in PoA that time travel is a circular loop. It does not have alternate time lines. For example, Harry always saved himself and Sirius from the dementors.
-What the hell was with the Trolly Lady? No. Absolutely not. I mean, the Trolly Lady went to Dumbledore's funeral. She is a human!
-Um... Apparently the Fidelus Charm does not exist on James and Lily's house since everyone can see it.
-Why is Harry's scar hurting again? Why can he speak Parseltongue again? He isn't a horcrux anymore. DH clearly establishes that as being the reason why he has those "symptoms," yet he experiences them again in CC.
-McGonagall is still Headmistress, even though prior to that Rowling previously wrote on Pottermore that she would be retired by then.
-MORE . . .

I didn't like it at all The story was uninteresting, the characters (and consequently, the actors) were bad and one note. It was a downgrade visually too, until now I haven't fully appreciated how much Stuart Craig did for the HP films lol

I am surprised at the amount of people around different discussion boards who consider this Yates' best HP movie. Yates' cinematography choices were much more interesting in HBP, DH and even in The Legend of Tarzan. It's not bad, it's just... pretty standard. It might be due to him working with more talented cinematographers back then in Delbonnel and Serra.
That said, Yates is still great at directing actors. Overall I enjoyed the movie. It had a lot of charm and I really cared about the characters. For me it's a solid start for this new franchise.