My kids decided to rewatch all of the Harry Potter DVDs this week, and watching them made me see a few things that bothered me. Overall I think the movies have been pretty good. I liked the third one best, followed by the first. The later movies suffered from being too chopped up. They should have learned lessons from Peter Jackson and released extended edition DVDs that flesh things out better.
The most glaring problem for me was that Lavender Brown was black in the early films and then was changed to white. I don't think it is too much to ask for some simple consistency.
Kudos to those who cast the films. The casting was so well done for most characters that I can't imagine them any other way than they look in the films. This does lead to another problem for me - the love interests don't work in my opinion. Watching the actors, Ron definitely doesn't fit with Hermione. She seems more suited to Harry. Ginny seems a better fit with Neville to me.
I was most disappointed with the latest film. The Half-Blood Prince feels so chopped up that some scenes don't even make any sense unless one has already read the book. There is too much cut out and there is little character development. From the Goblet of Fire onward there should have been extended editions at least, if not two movies for each book. I hear they will do that for the final book, so hopefully it will be better.