The best analogy between an audiobook program and a book is to think of the difference between a map and a navigator. When you're driving with a map, you can get where you want to go - especially if you take time to preview the map and check your location. But, with a navigator, you don't have to take your eyes off the road.
Since audio courses tend to be a little pricey, my recommendation is to get the book first nine times out of ten.
