lorde I'm mixed on that front, but mostly I prefer the novel over the movie. The visual medium is wonderful in its own way, but the time it takes to present an idea on screen versus explain it in a book are vastly different (and usually favors the book). There are some well-done adaptations, and there are some awful adaptations (and some that don't even deserve the term).
The novel usually gives me a better insight into the character motivations and the world around them. A movie usually gives me a greater feeling of immersion, how the pieces fit together, and brings life to a place that previously existed only in the imagination. Both are extremely powerful, but I lean towards understanding more of the motivations and world than seeing it in action.