You probably know DBZ films aren't 'canon' (non-canon = anime original, events of this movie doesn't happen in manga or LN), and people view them in very different opinions. Some people like these movies, others hate them.
I like the Tree of Might, there are things that I dislike, which are dragging this movie down. However, in comparison to other DBZ movies, I think these negatives are mostly minor. So, let's get into the review.
My Positives:
1, Art style and music are basically DBZ, looks good and sounds good as well.
2, The idea of a tree that devours the planet ecosystem to have a special power-enhancing fruit is quite interesting.
3, Turles: I like Turles, he isn't anything special, but I think the movie has managed to make him look like a decently entertaining character.
4, End fight: Fight has an excellent finishing of Turles with his tree of might.
My Negatives:
1, Turles: Lower class Saiyans often looks the same. Nope, you're just lazy :D. I don't mind Turles being Goku lookalike. I like the concept. I like it more than Goku Black, but saying lots of lower-class Saiyans looks the same as Goku is lazy.
2, Initial sequence: I'd have lowered its length to 5 minutes max and invested more time into Turles
Now Tree of Might has more positives and negatives to talk about, but these are the biggest ones for me. I don't want to write a long essay. It's not a groundbreaking movie, but I found Tree of Might to be quite good.
To finish it off, I give it 7/10. I think this movie is worth watching at least once. I won't mind rewatching it.