It's important first to say that I'm 18. This book is reaallly not aimed at 18 year olds. So, that was probably the reason it really didn't click with me.
However, I did enjoy it (even if I didn't find it useful) and so I'd definitely encourage younger girls to read it. If I'd been 13-14 I know I would have found it empowering, engaging, thought provoking and useful!
Written in the style of conversations between God and a teenage girl, important truths are developed. Though, some of the talking is repeated between chapters (apparently this girl misplaces her bible everyday!!) most of what is said is really thoughtful and I'd encourage girls still think about what's being said even if they don't relate to the narrator!!
Also, to any girls reading it, or thinking about it - please, remember to pray :) God loves you, and he speaks to us all in different ways. Though I have every faith Susie Shellenberger wrote this book empowered by the Holy Spirit, we must always reflect on these 'help books' and consider them alongside scripture! If anything in this book strikes a chord then please, find a christian you trust and talk to them about it, ask for prayer, seek help.
God Bless :)