Our small group recently went through the book and the DVD study series "Prayer Together" (based on this book). Everyone in the group discovered at least one aspect of their prayer life that could use fine-tuning, and the suggestions in the study and book were very helpful.
I have a copy of the original book by the same title. The updated stories and the addition of the final chapter in this version give the book a fresh feel. If your group is going to read the book along with doing the "Prayer Together" study, I would recommend purchasing the updated version of the book, since the chapter divisions have been changed from the original, and the reading assignments are based on the 2008 revision.
This is the second time our bible study group had use "Too Busy Not to Pray". This topic is relevant to our spiritual growth. It is well written, easy to read and comprehend and full of great material.
I Also purchased and like the DVD and think it adds to our study. Not so sure about the Study Guide. I think it is kind of expensive when added to the purchase of the book. Does not contain additional information, just helps guide the discussion. I think you can effectivly do this using the questions for discussion already printed in the back of the primary book.
I read this book 20 years ago. Our pastor recently mentioned it in his series on PRAYER. I re-read it and ordered a copy to pass along to others. Lots of practical helps as well as challenges to strengthen my own prayer life.