I loved this book when I was younger; I think age 13 or 14 is about the right age to fully enjoy it. Upon rereading it as an adult, I can't help but see the philosophical axe that Alcott was grinding in writing this and the other March family stories. Each March sister is drawn to illuminate some philosophical or theological belief of the Alcott group, and so provides a teaching experience in reading the book.
I'm not complaining too much--I still get excited when Amy and Laurie get together and it's still sad when Beth dies. And Jo is always everyone's favorite character because of her imperfections. What a great story.