I bought AA (B&N.com has it for the cheapest, I think, unless you go to Ebay and stuff which I don't know about) earlier this semester since I commute and I thought it would be a good use of time.
But, damn, if I never listen to Disc 4 and Disc 12 ever again I will die happy. Those are the only discs I played just because I thought it would help if I play it repeatedly and sort of memorize the material. Well, I did memorize it-- the cringe-worthy, lame jokes, mostly. Ugh...I hate it so much. Buy it only if you have high tolerence for obnoxious banter.
I've stopped playing the discs. I've realized it's better that I drive in silence for my 90 minute daily commute.