The convergence of all of the endings
To get the very best out of this truly excellent book, you really MUST have read the previous six in the series. All of the loose ends are brought together as you read your way through all the inter-twined plots and sub-plots and, with a nautical background, I would compare it to the back-splice that neatly ends a rope.
There is so much death and destruction that I would worry about younger children reading it, but those who have read their way through all seven books should be old enough to take it. I must admit that I shed a tear or two for some of the characters who are killed off in this final story, especially one of Harry's most loyal and trusted friends who meets a violent death about two-thirds of the way through. I won't spoil it for those who haven't read the book, but I'm sure that you'll share my grief; and Harry's.
The imagination that has gone into inventing new situations, and new escapes, for the main characters is incredible. Only JK Rowling could achieve such amazing surprises.
I just loved this book from beginning to end, and had to neglect the rest of my life, including sleep, whilst I read the last 150 pages. I am not kidding! I finished at 3.30 am, much to the annoyance of my wife who kept telling me to turn the light out.
My only negative comment is that I thought that the epilogue was pointless and unnecessary.
Do not miss this book, but read the other six first!