This cable connects to the IPOD via the dock connector at it's base, rather than the headphone socket that you would have to use with a standard AUX male-to-male cable. So what's the difference ?
Well, by using the dock connection, the car audio takes control of the sound rather than the IPOD (the IPOD volume level is ignored). You can manipulate the sound using your car stereo's volume and tone controls. In my case, this made a difference in two key areas - volume and quality. Volume was much higher than what I previously got from the headphone socket and my perception was that quality was improved - there seemed to be more clarity and crispness about the music and a fuller soundstage, likely, at least in part, related to the improved volume and tone control. For reference, I was using an IPOD Classic 120G.
The cable does appear to be a bit flimsy (though I don't think it would break easily in normal usage) and it does snag up without too much effort, but you shouldn't really need to mess about with it much, once you have found a satisfactory placement and suitable cable length that meets your needs. Like any standard AUX, it doesn't charge the IPOD, but at this price point that's not unreasonable.
Overall, this is a very good product for the price and will almost certainly improve your in-car IPOD listening pleasure over and above a standard AUX cable.