This story takes place a generation after the events in the Deathly Hallows. I enjoyed the opportunity to dive back in with these characters and see what kinds of people they have become as adults. And the core new characters, Harry's son Albus and Draco's son Scorpius, are well-realized characters that probably have enough to them to support another series (if they can find appropriate antagonists). The story is excellent, and manages to explore both the new child characters and the adult versions of the original characters. It asks some interesting questions, such as how important small acts can be in determining a person's fate.
That said, the execution of the story wasn't quite on the level of J.K. Rowling's solo works. While plays are certainly meant to be seen and not read, there were a few too many moments that seemed to be going for a chuckle or audience applause, and yet didn't do a good job of moving the story along or fitting in with the themes of the world. Nevertheless, it's a fast and enjoyable read, and is pretty satisfying given that it is the last tale we're likely to ever get of Harry Potter and his close friends.