When a story is well done, I can immerse myself in it and see it from a character's point of view. So I can still enjoy a movie with a big reveal at the end even if I already know the reveal.

On the other hand, some movies are simply too intense to be enjoyable for me. So I often pull up Wikipedia first to make sure that the payoff is going to be worth it.

An example that falls into both categories is "The Fugitive" (Harrison Ford movie based on the TV show). I already know who the villain is and who dies at the end, but I can still enjoy Harrison Ford piecing it together and Tommy Lee Jones trying to stop him. And the last part of the movie is more intense and action-heavy than I really like, but I can take it because I know how it turns out.

I sometimes joke that I'm a member of the "Wikipedia Film Club" because I read about more movies than I actually end up watching.