Heh, I still have one of these sitting in it's original box down in the basement. I still remember reading about it on slashdot, and getting in the car 15 minutes later, even though I already owned a DVD player.
I never made too much use of mine either. Video quality was rather poor, it crashed a lot, and it didn't like a lot of the MP3 CDs i fed it. I thought there were a lot of newer players that did all the stuff the old AD600 did, plus a whole lot more (like play DivX files burned to DVD) for not much more than $100. (I haven't really bothered to keep up, I just use my laptop these days...)