While not the worst film in the world, this movie suffers from two main problems that really hampers the film's overall quality.
The first being the film's rather cliche and underwhelming story. It's your typical "protect the animals/nature" plot, with about the only new thing done with it is it being set in Sardinia. Every plot point and story beat is practically the same as any other film of this type, and does nothing to try to either subvert this genre's tropes, or to do anything new with them. Kid moves to new place, finds some rare/endangered animal, greedy money grubbing villians come by to capture it, yadda yadda yadda, you've probably heard this storyline before multiple times.
The second main problem this film has relates to it's underdeveloped, uninteresting cast. You could sum up all of the major/importent characters in one or two short sentances at most, and even that's stretching it. Tottoi himself, for example, is simply "Naive and boyish", and that's the extent his characterization goes. The cast as a whole lacks any real depth or development to make you care about them, or the situations they find themselves in.
The animation, as well as the art style are servicable. It's nothing groundbreaking, even for when it was made, but i wouldn't call it nescisarily bad, either, and the backgrounds are suprisingly well done and rather pretty. However the animation can look rather lazy at points, with stilted movements, poses, and lack of detail at certain points.
Even with all this in mind, the one thing I think makes this worth a watch would be the voice acting. At least, with the english dub. It's one of those dubs that is hilariously bad, cheesy, and is a joy to mock and make fun of with a couple of friends. The voice actors range from cheesy and generic, with characters like Billia, to completely meme-worthy with characters like Pedru.
Unfortunatly, the laughably bad english dub is the only reason I could really reccomend watching this. If you're looking for a movie with an actually developed story and cast of characters, I'd keep looking elsewhere. But if you want a cheesy english dub to have some fun with, I'd defenitly check it out.