The NSX has two radio antennas: the mast, and the top third of the engine hatch window (which is often mistaken for defroster veins which comprise the bottom two thirds of the window). The radio has a diversity system which senses which antenna has the better signal and uses that one. Depending on the reception in your location, the reception from the window antenna may or may not be adequate.
Also, for those who listen to CD, remember that you can get the Smartenna to keep your antenna down while you're listening to CD.
The length of the NSX antenna never bothered me. After all, the reason it looks long is because the car is so low. Besides, I never have to look at it anyway; it's only extended when I'm inside the car.