There are not many books that have made me cry as much as this one did. From first read, you know this will not just be another LDS high school romance novel. For one thing, the character telling the story, Kathy, is not a member of the LDS church. She also feels a connection to her deceased brother she doesn't remember, and is sick of hearing about how great he was all the time. In fact, she feels like after he died, her family ceased to move on. When Kathy receives a mysterious gift from that very brother on her sixteenth birthday, she and her family will embark on a journey that will lead to greater love, understanding, and healing, as well as the possibility of blessings beyond this life. Yes, there are definitely romancy parts, some of which seem to wrap up a little too neatly (after all, it is a teen fiction/YA book), but the overall driver of the book--that secret journal, and the effect it has in the lives of the characters in the book--keeps the pages turning (and the tears coming) long after the light should be out. :)
The romance in this book is very clean (nothing more than simple kissing). If you have specific things you have counseled your children to avoid or to do during the dating years, I recommend reading the book yourself first so you can reinforce/talk about your specific standards as they are reading.
For anyone who is learning more about family dynamics and how things like grief and religion affect family members, and how conflict and misunderstanding can be avoided, this would be a great novel to dive into.