"The Sisterhood of the Traveling Pants" is about four teenage girls who spend a summer apart but keep in touch by mailing a pair of jeans around the world to each other. "Sisterhood" is about teenagers but not meant just for teenagers. It would be enjoyed by anyone who could savor a complex patchwork of human stories that weave together over a summer's time. They aren't earth-shattering stories but little personal ones that mean a great deal to the characters.
"Sisterhood" strikes a perfect combination of tone and pacing, and is sentimental for sure, but not sappy, and fun but never silly. It's also incredibly beautiful, featuring some stunning panoramas shot in Greece and Mexico.
By the way, try not to confuse "The Sisterhood of the Traveling Pants" with a piece of drivel called "Divine Secrets of the Ya-Ya Sisterhood." They’re nothing alike.
[2009: "The Sisterhood of the Traveling Pants 2" wasn't bad, either. It was a little watered down, as you'd expect, but it worked pretty well.]