Visually this is still stunning. The world and the characters have a unique style, that doesn't really look older than it was 40 years ago. This is very impressive.

Storywise this is extremely simple, and Gen is the most stupid and useless hero ever.

I mean there's this mystical crystal that holds the whole world together, it has been broken a thousand years ago, bringing disasters. He first needs to find the missing piece. It was a very long time ago, and it's super important. Is it lost ? Is it hidden ? Is in an inaccessible place ? Is it guarded by a powerful monster ? No, no. We know where it is, you just walk for a day to get to the right person, then just ask and you'll receive it.

Then he doesn't know what to do with it. For a pretty long time. Until he finally sees a prophecy on the wall and understands that he's meant to bring the small broken piece of crystal to the rest, and fix it. Which is like, duh. You're sent to find the missing piece. For what else than fixing it ? This is also basically the first thing he's told by his master at the very beginning. Word for word. But he probably wasn't paying attention.

He's then basically useless, and thankfully Kira is here to make things happen.

Probably still works very well as a children movie.