I've had my D7000 since January and have shot many images with it. It was an upgrade from the D5000 that was an upgrade from a D40. At the time I bought another book that helped me become comfortable with what I thought were most of my camera's capabilities. I've gotten a lot of nice pictures using it. Still, there were some functions that I did not fully comprehend even after reading about them several times. The focusing system was one of them and not understanding it has left me with some out of focus images that I really wanted to capture properly. I knew that the limitation was my lack of understanding and not a problem with the camera itself.
So, I bought the Kindle version of this book. What a revelation! It gave me a newer, more powerful camera without having to buy a new model. After reading the sections on the autofocus system and picture controls I modified some settings on my camera. My image quality immediately improved and my percentage of usable shots went up. Looking back, I wish now that I had gotten Darrell's D5000 book when that camera was brand new.