Yes, watch none of the film adaptations of A Little Princess before you read the book. The modern version is better, but still not the same.

I don't condone Burnett's more New Age-y excesses (she was a great proponent of Theosophy and Spiritualism, her era's equivalents, and it leaked steadily into her writing) but somehow she did get a power and presence into her stories that's not quite definable as anything but magic.