As far as anime movies go, there are a bunch that are well-known and “high-profile”, especially the ones by Studio Ghibli, Makoto Shinkai or Mamoru Hosoda. Sakasama no Patema does not belong to any of those categories, and so I doubt it’s as well-known as, for instance, Garden of Words or Wolf Children. I think it deserves to be watched, though, if only for its “gimmick”, i.e. the fact that the force of gravity is inverted for Patema (and some other characters).
Sakasama no Patema is not a perfect movie. The story relies on some fairly boring “damsel in distress”-type conflicts, and the characters aren’t the most memorable, but the movie does have its strong points. The one I remember the best is the comedic timing of one of the early scenes between Patema and Age, where the background music stops and continues in sync with the dialogue in a really funny way. Unfortunately, that’s about it when it comes to my memories of any funny scenes in the movie, but it’s something.
And as I alluded to above, the inversion of gravity is one of the most interesting aspects of the movie, the main reason being that it’s not a super common element, especially not on such a global scale. Patema having to adapt to living upside-down is interesting to watch, and it occasionally sets the characters up for some pretty fantastic-looking scenes. I don’t want to spoil too much, but there’s a lot of flying around.