Your opinion of audio books are probably going to depend a lot on your age, if you can remember 33, 45, or even 78 speed phonograph records or if you are going what the heck is a record, it will play a large part in your feelings towards audio books as a medium. To the very young, not capable of reading yet they are a joyous and entertainingly vivid way of experiencing the written words long before you can put together your first "See Spot, See Spot run".
To the highly mobile teenager they are the closest many would ever get to a book if not held in captivity seven hours a day in our public schools being forced to read things they can no more relate to then a Eskimo can to the sandy deserts of Saudi Arabia. Let's face it although considered the greatest playwright of the last millennium Shakespeare is so out of touch to the average teen that you might as well drill a hole in their head and poor the stuff in as get them to want to read it.
Once again the generation gap will play a large part in whether you feel books by their sheer nature are better than audio that can just be turned on at the press of a button from their mp3 player as where their grandparents are asking what is an iPod? When seeking to find the answer for the question are audio books better, equal, or just a fad, you have to look at how the two differ.
The pro's for the audio side of the argument; goes anywhere, light, hands free, can be read (listened to) on the go whether in a plane, train, or automobile. Costs are now comparable with the written book and sometimes actually more affordable.
You do not have to worry if you spill your coffee on an audio CD - just a quick wash and it is going again; try that with your favorite Harry Potter Book. You can often get audio books read by the author so there are no questions as to the author's intentions about the way a passage was meant to be read in the book.
It is probably that fact which is one of the most vivid reasons that the audio books have a flaw. Where is the imagination? When you read a book, you have to interpret in your own way what the author meant by a passage not someone else's view of it. You have a clear blank slate (ancient devices to write on with chalk like a PDA without batteries) to draw your own vision of the words with their own smells, sounds, lighting, mood, and whatever other senses you choose to employ in the visualization of the written words.
As humans we need to ask ourselves what is the reason for us to write books and thus hence audio books? It seems clear that audio is the offshoot of the written (for the last 100 years or so at least) not the other way around. Not too many authors release an audio book then release it into print.
On the other hand, studies have shown that only about 10% of books ever get read passed the first chapter. We have to ask ourselves what we are reading the book for in the first place. Is it for technical information or for the sheer joy to sit down with a hot cup of your favorite brew and find a cozy quiet corner to escape to lands far off and forgotten?
One could supposedly take this question one step further and ask whether the movie is better than either a book or an audio? Back to the Harry Potter example, are the movies better than the brilliant works of magical words that JK Rowling's scribed out over the last decade? Are the visualizations of Alfred Hitchcock's The Birds or Psycho clearer in his written words or the film later and then what about colorization?
The human mind is a complex visualization device and one left to its imagination creates incredible visions of what we see, or read, or hear. In conclusion one needs to ask yourself whether you want your medium dished out to you pre chewed or would you prefer to sink your teeth into a nice thick juicy steak and saver every single morsel of its complex texture, smell, taste, and visual perfection?
In the end if it is a question of getting some exposure to great books than it really does not matter which you choose as long as you get some of the great literary works of mans' colored history to experience. One could also ask the question what about ebooks, but that would be yet another whole debate in itself and beyond the scope of this article. Whichever you decide in the end will be just fine as any opportunity to engage your mind from something other than the TV is a good one.