This is my childhood right there. I remember watching and re-watching this movie that we had taped on a VHS long ago. Many people have movies they deeply moved as children that they could watch over and over without being tired of it. This was mine.
To be honest, the art and animations are miles away from current standards, but the story was good and appealed to young me. The story is more mature than that of most other movies for kids, but in my opinion that just makes it a movie with a wider appeal that you can watch again as a teenager or even an adult, seeking a taste of their own youth. The story takes a lot of elements from fantasy clichés, which makes it especially interesting for creative youngsters who are attracted to tales of knights and dragons, as I was.
There are also dark and sad scenes and it can be pretty serious at times. People and animals, good and bad, die in this movie. And not just "going to sleep", but in scenes of violence.
The story is basically this: the world of science of man is intruding on the world of magic, so the 4 wizards who rule it gather to decide what to do. 3 of them agree to build a barrier to separate the two worlds for good, letting both continue to exist, but the evil red wizard wishes instead to use magic to influence the world of men to destroy itself from the inside by laying waste to the Earth, so that he can rule the ruins. To fight him, one of the wizard summons a man of science from our modern world, but because of a magical mishap, he ends up in the body of a young dragon. There starts a quest to end the evil wizard's power by destroying his artifact of power, his crown.
You can say that the story is just classic, nothing really new or thrilling... but classics are classics for a reason, because they appeal to us and just work. It's the case here.
I highly recommend this, especially since it's out on DVD now.