Pros: Easy to use, convenient, sounds good.
Cons: Needs a strain-relief where the cord connects with the 12v plug.
I bought this as a gift for my girlfriend. She uses it with the Aux input jack in her Mazda3, and it works wonderfully. We particularly like the audio output at the base of the unit--that means that only one cable has to come out of the center console to connect to her iPod. We use a 12" cable between the Belkin charger and the Aux input, which keeps the cables to a minimum.
However, after about three months of use, the connection between the cable and the plug that connects to the iPod started to come loose. There was apparently no strain relief on that section, and the individual wires became visible as the outer jacket worked its way out. About two weeks later, it stopped transmitting music.
Thankfully, Belkin has a lifetime warranty (with an express replacement option). The replacement came very quickly; we just had to pay to ship the broken one back to Belkin.
Also, be aware there is a volume control knob on the side of the 12v plug -- make sure you set that carefully to help eliminate noise/interference.
The only reason this product does not get 5 stars from me is because of the strain relief issue. Otherwise--it's terrific!