Spoilers are a complicated subject. The premise of GROUNDHOG DAY was spoiled in the posters at the theater, yet it's played like it's a big surprise.
OTOH, the best moment of the "New Star Trek" for me was the movie trailer, which showed the motorcycle chase without identifying the movie, so I got to be surprised at the end of it, as they blazed STAR TREK across the screen ... that was great. Note that the movie itself spoils the outcome of this scene.
Good stories work even if you know the ending, stories that get spoiled because you knew the ending stink. Classic Greeks would know the story before going to the play, opera goers often have the libretto with them.