I've owned this book since I was in middle school, maybe even late elementary school, and I've always just had it around. While it does have a lot of good quotes in it, there are also a lot of quotes that I feel don't apply to me or, if used in conversation, don't sound as exciting to explain when someone asks where the quotes came from. It's cool that they quotes a fifteen year old in their book, but at the same time it's not something you'll hear quoted a whole bunch of times. Other quotes were just weird ones - things that weren't necessarily inspiring or useful for quoting to others. Like there's one in the romance section about Nicole Kidman and how she made Tom Cruise (her husband at the time this was published) take her out on dates regularly. Sure, it's a neat tidbit and it might inspire people to make their husbands take them out on dates, but it's not something really quotable. Other quotes were great and really inspiring ones. I found I particularly enjoyed quotes by Helen Keller and Bella Abzug.
Honestly, I don't feel like this is a book that would be of interest to girls past the middle school age range.
Also, as someone with a graphic design degree, the erratic use of weird fonts drove me a little crazy, but that's just me.