I can think of very little to say that hasn’t been said in the previous seven pages, but I’ll try.
First of all, some of you read this novel much faster than me. And in another thread, someone was amazed that the book sold over eight million copies in the US on the first day, but on his show Keith Olbermann mentioned that the book sold 72 million copies worldwide the first day, which is absolutely astonishing. (And Olbermann showed video of himself in line to buy the book at the Scholastic Book Store in Manhattan with Salman Rushdie, of all people, in front of him in line.)
Re: Fred’s death. I remember hearing that JK Rowling wept after writing the ending, and I think she wept over his death. (Supposedly she finished the book in a hotel room, and left a bit of graffiti to that effect in the room.)
And when Harry, Ron and Hermione were on the run and were camping out in the countryside, Hermione complained about how hard it was to find decent food. But when Dean and the others were able to locate good salmon immediately when they camped nearby.
And I was a little disappointed by the mention of Slytherin in the epilogue. Separating the students at Hogwarts into separate schools seemed negative at times, so I thought perhaps in the wake of the battle that they might eliminate the separate houses.
And I would have liked to have heard more detail in the epilogue about what happened to everyone. I even wondered where they lived. Did Harry and Ginny set up house in Number 12 Grimmauld Place, with Kreacher perhaps as house-elf? (And the fact that the house was invisibly between Numbers 11 and 13 indicates the difference between British and American house numbering, since in the US, 12 would most likely be across the street from 11 and 13.)
Diadem: I thought the diadem was hidden (like Poe’s Purloined Letter) in plain sight atop the statue in the Ravenclaw dormitory.
And, while I’ve been beaten to the punch on this suggestion, the obvious follow-on is “Hogwarts: The Next Generation”, with Prof Longbottom, Headmaster McGonagall and their wacky students along with Peeves, the school ghost and comic relief figure.