I have audio osmosis and have found it quite helpful in refreshing concepts that I have forgotten from past semesters. It's especially beneficial for me because I commute about 1.5 hours a day.
If your plan is to sit in your room and listen to them, forget about it....get the books. I would definitely recommend audio osmosis to anybody who has time to pay attention to the cd's while doing something else (work, driving). If, however, you plan to just settle in to listen to them totally focused on just the cd...you will bore quickly and you will have wasted $200 (or $150 if you buy them at www.alibris.com
Either way, you need to buy examkracker's complete study package (also at www.alibris.com
)...their books are sweet.