Cures from several seasons interact with each other and fight a big bad guy. If you're fond of any of the relevant characters, especially Hana, Saaya, and/or Homare, you'll enjoy the movie. Its structure isn't that different from a typical episode of Precure, it's just longer and has better animation. Watching the Hugttos and the Kirakiras get together was really cute and fun, and the final fight was pretty exciting. The Mahous don't get as much screentime but they're around. The morals about keeping promises are important for anyone to soak in I think. Also the opening track is one of the better ones ofthe franchise in my opinion.

In the end it's a Precure movie. Even if it's not as good as other Precure movies, it's going to be at the quality of or better than many episodes of Precure. And you enjoyed those, right?