The book so far, I can tell is going to be pretty good. I like whats going on and the plot is beginning to pick up at a steady rate. I'm about a fourth into it and it looks great. And even though I like as much as I do already, people have told me that this is the worst book in the series. The series must be pretty good if that's the case.
As for my visualization. For some reason, unknown to any, I don't visualize the characters of Harry Potter like they are in the movie. To me, I keep seeing them as the characters from construction paper cutout show South Park. I can't unsee that. I don't know why.