Generally, I prefer reading books to watching a film based on a book. And usually the book is much better than the film, because you use your own imagination and everybody has his own thoughts, feelings, emotions, while reading a book. Most of the films do not meet these very personal and individual feelings and associations. Therefore, it is difficult for me to say it was good that a particular book has been turned into a film.
However, there was a film that I liked a lot and that based on a famous novel: „Homo Faber“ by Max Frisch. I think the film was in the cinema around 1990 and most of my readers probably do not remember that film. Of course, there were a few differences to the novel, but in general my expectations were met.
As a more recent example I would like to mention the first part of the triology by Stieg Larsson, which met many of my expectations, especially concerning the actors, although I like the books better.
Finally, I would like to mention the movies made on the „Harry Potter“ series. Even if they do not meet my expectations in every detail, these movies are a grand piece of art and I enjoyed watching them.