I had a Kenwood Z828 in my 2001 Integra LS, but when I traded it in for the Type-R, I left it with the car.
I've reverted back to a normal CD player and I hate it. You only get up to 80 mins on a disc, as opposed to the 10+ hours I got before.
People are going to mention that quality is lacking on the MP3 deck, but that's only if you use low quality files to fit more on a disc.
I had the first generation Kenwood model, so there was like a 1 second pause between tracks, but that was eliminated with this year's models, so go MP3!