This is one of three couples devotional books my husband and I have read and it was our least favorite. To be honest, we did not even finish the book.
I believe that daily devotions with your spouse are a great idea. However, there are much better books out there. There were a few topics which were useful to us, but following the book from beginning to end was not practical because many of the devotions deal with specific topics which don't necessarily apply to all couples. Also, in order to completly cover the lessons, it took us far more than 15 minutes. We spent more than 30 minutes on most of the ones we read and didn't feel like we really completed them. Another issue which bothered me is that there are not discussion questions each day. Generally they suggest you write about a topic in a journal. That style may be great for some but the lack of discussion questions left us feeling like there was something missing.
If you want a good couples devotion book, consider James Dobson's "Night Light." Reading it was one of the best things we have ever done for our marriage.