If you've had a digital EOS before, then there is very little in here that isnt already in the manual you get with the camera. That could well be that the 50D is so similar to 40D, but I was expecting a little more than this book delivers.
For a relatively inexperienced digital photographer this book will be my next step in the learning process. I am reading Jeff Revell's Canon 50D From Snapshots to Great Shots first as this book is the perfect introduction to the 50D. I am following the recommendation made in another review.