Hey, I've got one in my car! It works tremendously!
But the AVX-7000 is just the display. You will need the central unit with the built-in amplifiers and FM tuner as well. I've got the AVM-P7000R, that's a 4 x 45 MOSFET amplifier and has an IP bus (pioneer thing) that connects to a 12-CD changer. You can also connect a TV-tuner and a VCR. It has AUX in and Pre-OUT, subwoofer-out and a Video-OUT, and also two Video-IN plugs. The video-in I'm using to connect to my MP3 CarPC.
If you are considering buying one: today Pioneer has two new models, the "8000" and the "9000". They work fine with the AVX-7000 screen, and they provide you with DTS, digital theater sound, AND a 6 x DVD-CHANGER! Realy cool!
Almost forget one thing: you can add a GPS navigation system as well (at least I did).