Old-fashioned racism aside, I enjoyed the tale of the young orphan Mary growing out of her spoiled bratty ways alongside a garden (symbolism!). After the death of her parents, Mary moves from India to England to live with her emotionally distant uncle (played by Mandy Patinkin in the Broadway musical version!) - a hunchback so heartbroken over the death of his wife, that he forbids anyone to open her garden and also refuses to spend time with his sickly son. This book really brings out the happiness. Anyway, Mary of course stumbles upon the garden. With the help of her new-found friends, is able to bring life to the garden, the sickly son, and herself.
The Secret Garden is definitely a novel you have to approach through the eyes of a child, otherwise it just seems kind of bland and full of forced enthusiasm. But through the eyes of a child, it's obvious how the uncovering of a secret garden and the use of "Magic" to revitalize said garden (and people) is wondrous.
Now about the racism. Cracked covers it in more detail, though I disagree that the book is "secretly" racist. It was pretty clear from the get go to me. I think even children (today's children) would pick up on it rather fast, especially with this quote:
"a lot of blacks there instead of respectable white people."Yikes!
Now, if you were using this book as a school lesson or library activity (though I think it's best used as a read aloud at home or for a college paper on children's lit), the obvious activity is to make your own secret garden. Either real or in diorama form.