In case I haven't stated this before: this kit is THE BEST!!!
Sound quality is perfect, install is easy, no 80 min blank CD (I had the other aux-in for a while) and it just works. You don't even have to keep your radio in CD mode: flip it on and sound comes out, radio or CD mode.
Auto-switching works awesome. Only problem I had with it: using it as my hands-free for my cell if I am talking too long and the other person is listening and not making noise it'll switch off, which means the radio comes back on while I am talking. So I put it in "always on" mode and its perfect.
My CD player in my Subaru is totally dead. The usual cd changer jam that seems to happen to these after a few years (of playing the same blank CD all the time...) and this still works perfectly.
So GET IT! If it fits your car, get it. The difference in price is negligible compared to how well it works. Its less than 2 tanks of gas here in CA.