Saw the two part version in London cause I'm a fan of the books and movies. What a money grab.
Set: For the amount of money paid the set is embarrassing - metal stairs and suitcases for props for the majority of scenes with not much else aside from tables/chairs/a bed where relevant. The background is a clock and that's it, for every scene. It just felt lazy.
There is so much more that could have been done to bring it to life and make it feel like you're in Hogwarts/the wizarding world. I saw 2 other shows in London that month and they had the most intricate sets that changed each scene.
Story: The storyline doesn't fit with the Harry Potter universe, the characters don't seem like themselves - it's more like fan fic. Like can you imagine orphan Harry Potter who's grown up his whole life without a loving family, now as a matured grown man telling his child "I wish you were not my son." Would not happen. You could hear the collective gasp in the audience, it is so out of character.
Entertainment value: As a theatre show itself, well, I started falling asleep in the first part. I needed to do a long walk during the intermission between the two parts to wake my brain up. Luckily the pacing picked up in part 2.
Seating at the Palace Theatre: I paid a lot to be in the first couple of rows in the first level circle because I'm quite short and the ground floor had no rake. Although I could see the stage clearly I couldn't see any faces/expessions which was disappointing. Which made me question if there are any "good" seats in this theatre.
Anyway, I had to see it cause I was a fan and it was on my list but they really should have put more effort in to make it seem less obviously a money grab.