tbh I bet the best thing about the film would be visuals and jokes, and the trailer already spoiled a load of those.
Most likely, and those were the things I feared him spoiling because whenever you talk about the film you're more likely to talk about scenes you liked rather than the story as a whole. I watched a few clips to get an idea about what the movie is like but I'd like to think there's 95% that I haven't seen.
I mean I wouldn't really care if someone spoiled the story to a Mario platformer (mostly because such a task is impossible) but I wouldn't be so keen on someone spoiling the interesting levels.