Is an FM transmitter as good as a direct connection to your stereo? No. Can it sound good enough to satisfy your tastes? Probably, if you keep several warnings in mind.
First of all, performance can be poor in large urban areas. Especially here in Los Angeles, where not only do we have competition for the airwaves with local stations, but mega-transmitters from further south (advertised as based in San Diego, but actually transmitting from Mexico) stomp merrily over broad ranges of the bandwidth.
Your FM transmitter must be able to put out a strong signal, even while being restricted by the FCC. The AirPlay's design allows a strong signal. Your transmitter should also allow you to select from as many different frequencies as possible. Inexpensive transmitters often have only one to three frequencies. The AirPlay can select from nearly the entire FM spectrum. The AirPlay allows you to select your frequency directly, rather than using a downloaded file on your iPod.
