Most of this movie is the Dragon Ball Z trope of Goku and friends getting their butts kicked until (literally) the final 5 minutes of the movie. He shows up and is completely invincible until time is running out on the feature.
Broly represents everything that was creatively wrong in DBZ. I loved Dragon Ball and DBZ was great as well, albeit with a lot of faults. I first watched DBZ (as well as the original Dragon Ball) in 2015. If you do feel free to put your hands over your ears and exit the review. Not only is Broly not the best DBZ film, Broly is just plain bad. People often cite this movie to be the best DBZ film. For a non-canonical character, Broly receives a massive amount of praise. Welcome to the complete and utter letdown that is Broly.