You probably know DBZ films aren't 'canon' (anime original, events of this movie doesn't happen in manga or LN) and are viewed in very different opinions. Some people like these movies, some hate them.
I kinda like Tree of Might, but at the same time there are things that I dislike, which are dragging this movie down. So, let's get into review.
1, Art style and music are basically DBZ, looks good and sounds good as well.
2, The idea of tree that devours planet ecosystem in order to have special power enhancing fruit is quite interesting.
3, Turles: I like Turles, he isn't really anything special, but I think movie has managed to make him look as an decently entertaining character.
4, End fight: Fight has a really good finishing of Turles with his own tree of might.
1, Turles: Lower class Saiyans looks often the same. Nope, you're just lazy :D. I don't mind Turles to be Goku lookalike, but saying lots of lower class Saiyans looks the same is lazy.
2, Initial sequence: I'd have lowered it's 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 and I don't want to write an long essay. It's nothing groundbreaking, but I found it to be a quite good movie.
To finish it off I give it 7/10. I think this movie is worth to watch at least once.