Our church recently finnished the 40 Days of Purpose campaign where everyone went through this book a chapter a day for 40 days. This was coupled with sermons on Sunday and a weekly small group meeting. The intent was to use this campaign as an outreach to the unchurched community. In that respect I would call it a success. God used this campaign to bring many people to church who otherwise might not have come.
The book had it's good points and it's bad points in my opinion.
First, the good points:
1) Rick Warren does an excellent job of describing each of our purposes in life. Things that God made us for. I can find no fault in the 5 purposes. (Worship, Fellowship, Dicipleship, Service, and Missions)
2) The book is theologically sound overall. I have been a Christian for over fifteen years and an avid Bible student for the past 5 and I can find nothing docurnally wrong with the material presented in the book. There is very little denominational slant in any part of the book. Even though Pastor Warren is Southern Baptist, he does a good job of avoiding the disputible matters that divide churches.
3) For the new Christian this book is wonderful. We have some friends who recently became Christians and this book was a wonderful introduction to the Christian faith.
Now for the bad points:
1) I did not care for the way Bible passages were represented in the text. All scripture quotes were italicized but no reference (book, chapter, verse) was given in the text. You have to look in the back of the book and then it is only a list so it's difficult to determine which is which. I enjoy studying the Bible and would like to have been able to look up the verses in my Bible as I went through each chapter. This would also allow me to understand the context of the passage presented.
2) As others have indicated there was too much use of the Message translation. Don't get me wrong. The MSG is fine if you like paraphrases. However, as a mature Christian I think the MSG is far too "dumbed down" for me. I understand Rick Warren's desire to present scripture in fresh ways. But there are other translations that do this and are still readable without being over simplified. (The NLT for example.)
3) The book was far too repetitive. I found myself noticing the same material being presented again and again. It almost seems as if this was necessary to stretch the book to 40 chapters. (ie: 40 Days) Repetition is fine for some but not all.
4) Finally, there seemed to be little real-life application. Particulary in the later chapters. This surprised me a bit since I've heard Rick Warren teach before and he's always been big on application. There was plenty of conviction on what we should do but apparently little on how.
All in all I think it was a good book for those new to Christianity and those seeking to learn about it. It would also be good for someone who has grown stagnant in their Christian growth. For my part, yes I learned some from it but it was nothing I couldn't have learned from any one of a dozen Christian books.
One final note:
The whole marketing campaign with everything under the sun for the Purpose Driven Life (T-Shirts, Bible Covers, Journals, Prayer cards, etc....) has gotten a little out of hand.