Well, I ordered the whole deal...the textbooks, audio osmosis and the extra problem sets.
I have always been a visual learner, so I find cracking a textbook more productive than listening to lectures so I am biased for the texts. But I find the tapes useful when I'm away from the books for a chunk of time regularly. What I mean is, since I cook, I like to turn them on so I dont' waste time while cooking, same goes for doing household chores. I've heard others who have long commute found them a timesaver. If you are an audio learner, I think they would be good, although I still think it's good to have the text, especially in orgo and physics. But they are a good supplement to the textbooks.