No, never read the HP books. It's not easy to compare a book to a movie. In a book, the author can create whatever he wants, and you the reader create it in your head. To then see the movie where they film maker cannot make everything, and even if he did, it wouldn't match what you created in your head.
That said, I thought the Lord Of The Rings movies are great, if not completely faithful to the books. I read mostly SciFi as a kid. Asimov, Bradbury, etc. Few were made into movies ( The Illustrated Man, not very good). Look at I Robot...at least they didn't try to make the book, they just took some principles, and made a different movie. And I liked that.
Sometimes I've seen movies, then not liked the book as much when I read it after. Some movies need to be taken on their own, that's harder if you've read the book. A Guy