1. Brolly is the worst character ever. All he does is use "big muscle slam attack" continously, shoot blobs of Ki, and scream KAKKAROTO!!! Which, he should not even hate that much. Wow. Goku cried when they were babies. Big deal. Like that would actually cause him to want to dedicate his life to nothing but killing Goku. And look, King Vegeta stabbed him and left him for dead. Why not make him want to kill Vegeta in the movie instead, since he looks like his father?
2. The action is terrible. "Big muscle slam attack" and "random blob of ki" get stupid and boring after a while. And Goku would NEVER really charge directly into someone who is stronger than him's ki blasts. EVER.
3. They made Vegeta look like a coward. We all know him. Vegeta would never back down, no matter how strong the person was. It would make him want to fight them more. Go watch the Android/Cell saga to find this out. And it looked like he was pissing his pants over the fact that Brolli was the "Legendary" SSJ, when three of his teammates were already SSJ, so the legend had been disproved.
4. The way Brolli "died" was retarded. Somehow the horribly beaten up Z Fighters giving the severly weakened Goku their Ki the very small amount of ki they had left allowed him to be STRONGER than he was before the fight. STRONGER. And a lot stronger it seems, because he was able to kill Brolli in one punch. No. Just no.
Overall, this is one of the worst DBZ movies ever.