I am going to be a little generous in this review, but not overbearingly so. While I enjoyed most of the plot it felt as though a child had written some of the story which I can get past because the moview introduced a lot more humor than I think we've seen in a DB movie for quite some time. The light-hearted nature of this film didn't take away too much of the peril at the end of the film.
My biggest criticism was that some of the animation wasn't as fine-tuned as it could have been, especially when it came to scenes involving Vegeta and Goku and their sparring match. The thicker lines on small images made it seem as though we were watching a poorly rendered cut-scene from Dragon Ball Z: Kakarot. Not terrible, but certainly distracting.
SPOILERS AHEAD
Some of the things I loved:
1. Piccolo summoned the dragon for the first time since Dragon Ball
2. Piccolo got a somewhat significant power up which now puts him on par with Super Saiyan 2, in my opinion.
3. We got to briefly see teen Goten and Trunks, though I would have preferred to see a non-fat Gotenks.
4. The development of Vegeta gets better and better and I am happy they finally gave him a concrete win over Goku lol
5. Training Broly to control his rage
One other thing I felt was a miss was Gohan's new transformation. In terms of design it looked fantastic, but I would have liked to see more of it in action. They did pay some fantastic homage to SS2 Gohan's original fight with perfect cell; the kick to the stomach, the stalwart glance as a massive Kamehameha wave comes at him from above. That was beautiful.