It depends on what you are looking for. In my experience, the sound quality has been a bit below FM stereo. For audiobooks, it is fine for long drives, but if you really want to appreciate the music, you'll be disappointed when comparing it to "line-in" or to a cassette adapter. It IS better than nothing. I have used the Griffin iTrip with my iPod and the actual working of the device is fine. I tend to use the "87" frequency to listen.
They're decent.... and if you get one, be sure to avoid iTrip, and get one that can actually charge your ipod while you're listening to it. The Monster ones seem to work best.
