The 12V power connector is small and short, the same diameter as the actual jack and sticking out by about an inch. It has a small white light to indicate that the TuneCast is powered.
The TuneCast worked perfectly with my iPod nano. It was as simple as plugging it in to the car's 12V jack and the nano, then tuning to the same stations on the Tunecast and the radio. The nano itself could be used normally as if listening through headphones.
It was the same story with the iPod Touch as the nano. The TuneCast was very easy and simple to use with the Touch.
With respect to the TuneCast itself, changing stations was easy with the two large + and - buttons on the front, and frequency changes were almost instantaneous. The Clearscan feature on the other hand wasn't very useful. I tried it out at a variety of locations in my city, and while it could find a moderately-okay station, the stations usually still had a little bit of static. It's much better to spend the time to manually scan and find your own good frequency to use. As you can probably tell, two good frequencies in my city are 90.3 and 92.7. Once I found these frequencies, music was clear and crisp. Sound quality was great for FM.
Honestly, I didn't even bother much with the Pro audio enhancement button. The settings did make a discernable difference in the outputted sound, but I personally like the flexibility of adjusting my stereo's equalizer myself to get the sound I want. Some Pro enhancements like amplification may be attractive to some who have trouble getting great sound from the TuneCast, but I didn't have that issue. I got great sound straight-up.
All in all I found the TuneCast Auto to be a great product. It met all of my requirements perfectly. It allows me to change stations easy, it charges my iPod while in use, it has great build quality, and the outputted sound is perfect for FM. It's too bad the Clearscan feature didn't work better (I wasn't very optimistic for this to work well). Belkin should either scrap that feature or make it work better. Belkin's TuneCast Auto with Clearscan for iPhone/iPod earns an 8/10 rating from circuitREMIX.