Dragon Ball Z Movie 3: The Tree of Might is the first Dragon Ball movie where invaders from space appear to destroy or take over the world. In this case they want to plant a tree that absorbs the power of the planet.
One of the aliens happened to be a Saiyan named Turles that resembles Goku and unironically has in the Japanese version the same voice actress. That can at first be considered stupid knowing that only 4 Saiyans survived but considering that even Toriyama ignores that rule to introduce more Saiyans to the main plot and these movies are alternative storylines that can't fit to the main continuity, this can be ignored.

The Tree of Might feels like a believable threat since like real trees it takes nutrient from the ground but far more than the planet can provide for every living organism thus leading to the devastation of the host planet.
The movies has good foreshadowing of what is to come in its beginning act which shows the importance to value nature before the real conflict even begins. Thus when Turles wants to take the live from the planet, it gives the feeling of something important being lost.
The film also succeeds on making the environment and its inhabitants important in battle since the more the planet decays, the more the feeling of loss comes closer for the good guys.
The movie also does a good job justifying the power of its antagonists and the cost. In this case the Tree of Might which drains the life force of the planet and bear fruits that give the users that consume it immense power from the planet. And considering the destruction it causes, it feels believable the power it provides unlike many other villains who are: Born strong, trained hard or transform to get stronger.
Since the invaders have done it several times, they are one of few Dragon Ball villains in general that have justification for their immense power.

Turles is a good villain and feels like a real Saiyan as he is obsessed with power and strength willing to sacrifice an entire planet and its inhabitants just to increase his might. He also shows that while he likes fighting, he won't stray away attacking from behind or using other dirty tactics to win. Even going as far as using the main characters as weapons to beat one another.

Icarus or Hire Dragon is a cute dragon child that befriends Gohan. And their relationship plays a role in this movie where they help each other out in difficult situations.

The movie did also a good job using the unused Z Fighters in this movie well like Tien, Yamcha and Chaotzu who alongside Krillin fight against Turles' henchmen. Even against an opponent they can't win, they still used their remaining power to hold off the last villain showing bravery and guts just to allow Goku to prepare his finishing move.

Goku also feels like an amazing character where he puts the safety over his son over immediately saving the planet.

The criticism about this movie is obviously with Turles looking like Goku and there won't be an explanation why that is the case except Toei trying to cash in on the popularity of Goku by making an Evil Counterpart of him that looks like him. In giving a hint what if Goku never hit his head and remained evil. That won't be the last time we see a Goku lookalike and it will get tiring. In the French version Turles is related to Goku. In the case like this, it would have been better if they showed a backstory for Turles like what planet he was sent or how it molded him to the destructive being he is. Or something so we can see a parallel how Turles experienced the world compared to Goku. But that doesn't make him less of a good villain. Obviously like many Z movies there is the use of power from someone else to put the finishing blow, but in this film it was done a more creative way because how the movie played with expectation of the viewer. Lastly the typical cliches such as Piccolo arriving to save Gohan.

In conclusion, the tree of might is an excellent Dragon Ball movie using the environment well to show the state of the battle and the contrast between Turles and Goku even if not done in a way it warrants the need to have him look like an Evil Goku. And obviously using all the important Z Fighters at the time in the movie showing the importance to stop the threat unlike in something like Dragon Ball Super Broly where only Goku and Vegeta fight while everyone else is minding their own business.