It is really not possible to limit a work of such purity by a rating, but for all practical purposes "Heidi" deserves at least a 10 on IMDb's scale, in my opinion.

The animation is so realistically done that we not only feel for all the characters, human and otherwise, but also live, grow, smile and cry with them. And the storytelling is at once engaging, visceral, harrowing, redeeming and deeply poignant. Every frame has some subliminal emotional content that draws us deeper into the narrative.

On a personal note, "Heidi" was by a far margin the best show I enjoyed in my childhood, not just because of the fantasies it weaved but also how intensely they were interweaved with all the harshness of reality. While that may not be necessarily the ideal content for children, the feeling of emancipation at the end of it all still rings true with me.

Johanna Spyri probably could not have asked for a better visual translation of her story.