I already own the book, but calculating the paces for different training programs has aways been time consuming. Thats why I downloaded this app. However, when I set it up for a half marathon training program, I discovered that its different from whats in the book. Its an 18 week program in the book, but only 16 weeks in the app. That seems to be source of the problem. Week 16 in the app is the same as week 18 in the book, 15=17, and 14=16. But then, week 13 in the app is the same as week 14 in the book, 12=13, and so on until week 8 in the app, which has a different interval workout than the books week 9, but is otherwise the same. Week 7 in the app calls for 4x1200 instead of 6. The book and app remain separated by 1 week until the apps week 3, which is similar to the books week 3 except for a different interval workout. Weeks 2 and 1 are the same in the book and app. I dont know if these are errors, or if they represent intentional changes to the half marathon program since my edition of the book was published (2007). If they were intentional changes, it would be nice if they disclosed that up front. But as long as you dont might a slightly different training schedule, it looks like it will do the job. I just wish it would calculate the interval paces in min/mile instead of just the time to complete each interval.