A few random thoughts - hopefully without too many spoilers ....
Watching the film really did feel like the end of an era. Harry Potter, films and books, has been part of my life for a decade, and whilst Pottermore will doubtless offer interesting and enjoyable material, the narrative circle is now complete. Along the way, I've been introduced passim to Joseph Campbell, Jungian archetypes and radical feminism, so my intellectual life is richer. Whilst Grint, Watson and Radcliffe may not be the greatest actors in the world, they have come to strongly shape the characters; the repertoire of British actors who have played supporting roles in the series have been excellent; and the achievement that is represented by holding the eight films together without destroying anybody's lives is substantial!
In many ways, I thought the film actually worked better than the book. There were certain things that were quite hard to follow in the book, which were made clearer in the film. Whether having read the book was required to follow the film, I'm not sure. There were also some deviations from the narrative sequence in the book. For example, some key sequences - the final showdown, and the death of the snake, amongst others - were presented in a way which made better narrative sense. These also made for better cinema. The increasing connection between Harry and Voldemort as the film went on was also brought out very well.
The fact that this film is largely action-driven for me highlights how character-driven is part 1. There was no shortage of action in it, but Harry, Ron and Hermione were allowed to develop through the film. Perhaps as a consequence, with the exception of the exposition at the start of film 2, it felt like a bit of a rush - one got the feeling that anything not directly related to the action was a kind of quick "Oh, we ought to show this about that character here ...."
The remaining Harry Potter event will be the release of the DVD, I guess. My daughter is already talking about a back-to-back showing. I'm not sure that I could cope with 20 hours, but I'd certainly like to watch the whole of "Deathly Hallows" in one go.